The struggle over the working day has long been central to Marxist analysis. In chapter ten of Capital, Volume 1, Marx chronicles the various ways that capitalists and states worked to extend the working day as much as possible, from the mid-fourteenth century up through the mid-nineteenth century. The reason was simple: the longer the working day, the more capitalists could exploit workers because after paying workers a subsistence wage, all labor done for the rest of the day was a surplus for the employer.

In the 1800s, the global working class united around the demand for a shorter working day. Subjected to sixteen-hour shifts, workers first fought for twelve hours, then ten, and finally eight. In fact, the origins of May Day lay in the international campaign for an eight-hour day.

Jump ahead to 2015. Many workers are still overworked, enduring lengthy work days and workweeks, and forced overtime. But a growing number of employees also face the problem of underwork: insufficient hours on the job, and erratic schedules that change day to day and week to week.

In some sectors like retail and fast food, workers may be hired for as little as eight hours per week — two shifts of four hours — for a probationary period of two to three months. To make ends meet, they try to pick up extra shifts from coworkers, or find additional jobs. They also agree to “on-call” shifts: making themselves available for work but getting no guarantee that they will actually receive it.

A recent survey of New York City retail workers found that only 17 percent of workers had a regular work schedule. Retail workers reported that in order to get more hours or more desirable shifts they sometimes had to compete with coworkers to sell a certain amount, or sign up the most people for store credit cards. In this way, they were battling with each other just for the ability to work and earn more.

This phenomenon is not restricted to low-wage service sector workers. In a 2014 study conducted by University of Chicago researchers, only 62 percent of young adults (ages twenty-six to thirty-two) reported that they know their work schedule more than a week in advance, and among hourly employees, just 59 percent are aware of the shifts they’ll be working a week in advance.

This means huge numbers of workers are adjusting their schedules on a weekly basis or less, making it difficult or impossible to plan care work, school, and other family and social commitments. In addition, the researchers found that nearly three-quarters of those surveyed experience fluctuating work hours each month, in some cases significantly — roughly eight hours of variation on average.

In the UK and New Zealand, employers have instituted “zero-hours contracts,” meaning the employer has no obligation to provide any work time at all. Instead, the employer schedules work according to weekly needs, which can vary from no time to full-time. Zero-hours contracts spread rapidly after the global financial crisis and today are prevalent in retail, hotels, food service, agriculture, and education. For example, one UK study found that only 4 percent of hotel and restaurant workers had zero-hour contracts in 2004, but 19 percent did by 2011.

“Flexibility” is promoted as a win-win plank of neoliberal labor market reform. Policymakers and employers argue that rigid labor regulations keep employers from remaining competitive in a fast-paced global economy, and prevent them from providing quality customer service. In theory, flexibility sounds good to employees too — particularly those who have to take care of children or elderly parents, who want to work from home, or hold part-time jobs.

In reality, flexibility has meant breaking unions and deregulating — or rather, reregulating — labor markets in ways that benefit employers at the expense of workers. Employers have more ability to shift the costs and responsibility of the employment relationship onto workers through practices like “just-in-time scheduling.”

Similar to how employers introduced just-in-time production to reduce inventory costs in manufacturing, service employers keep labor costs low through policies like on-call shifts — which mean that workers must be available, pre-arranging child care and so on, for a certain number of hours or shifts per week, and must call in the night before or morning of to find out if they are actually needed. If they aren’t, they don’t work and are not paid.

Of course, flexible schedules are not new. They’re still the norm in many areas such as the market for day laborers, or the “shape-up” for dockworkers. But with the advent of sophisticated scheduling software, companies have introduced a new level of precision to flexible scheduling. Now they set hourly sales goals for stores and if sales are slow (even if its due to something like bad weather), they relieve workers for the day.

On the other hand, if sales are booming and customer traffic is high, workers who call in will be told to report for work. Scheduling is often done at the last minute, with workers being notified of their shifts for the upcoming week on a Thursday, for a week that starts on Saturday. Increasingly, employers use software to break work into fifteen-minute segments, making it possible to send employees home fifteen minutes early if the customer flow slows down.

Fifteen minutes may not sound like a lot, but it adds up for multinational retailers and franchises with thousands of stores. A Jamba Juice executive recently reported that scheduling software helped the company reduce labor costs by 4 to 5 percentage points, resulting in savings of millions of dollars per year.

Nearly all major international retailers are using this sophisticated technology, but workers see no benefit. For example, employees may have their schedules generated online, but to get their actual weekly schedule they must go to the store and look at a bulletin board, or call into the store and ask a coworker to look at the schedule for them. They cannot request additional shifts, swap shifts, or cancel shifts online.

In a video from the scheduling company When I Work, employees are shown to have the option of seeing their schedules by email or text, and can ask for a shift change. But note that the boss must still approve the requests. The narrator says that the manager can alter the schedule from his phone, “while doing something more enjoyable than rescheduling everyone that wants to whine about their shifts.”

The move to more flexible scheduling has come alongside a shift from full-time to part-time work. One industry analyst reported that the retail sector went from being about 70 to 80 percent full-time jobs several decades ago to approximately 70 percent part-time jobs today. Retail employees comprise 11 percent of the US workforce, but 18 percent of those who are involuntarily part-time.

While erratic scheduling makes it difficult for someone not working a forty-hour week to find and hold a second job, relying on part-time work benefits employers — who can more easily vary hours and schedules, avoid overtime pay, and offer fewer benefits. Many companies have store policies that provide benefits only to full-time workers, and the Affordable Care Act applies only to workers employed thirty or more hours per week.

In the past, unions and policymakers imposed protections that made work more secure and stable. Beginning in 1939, the United Auto Workers included contract language mandating a minimum number of paid hours per shift, and by the 1980s most collective bargaining agreements included call-in and “reporting pay” language. And in Europe, many unions won some protection against irregular scheduling through collective bargaining or industry-wide agreements.

But as union strength declined and governments began reregulating labor markets in the 1990s, predominant ideas of “flexibility” enabled employers to erode or eliminate many of those regulations.

In the early 2000s, the European Commission began promoting “flexicurity.” First developed by a Dutch academic in the 1990s, flexicurity is designed to make it easier to fire workers and use temp agencies, while generating higher job security for workers in flexible employment arrangements. But research shows that the concept is difficult to realize, particularly when policymakers continue to push and prioritize neoliberal macro policy and labor market reregulation.

In reaction, workers and their organizations in the US and Europe have launched campaigns to win more stable and predictable schedules, ideally with minimum work hours. Activists assert that fighting for a higher hourly wage is limited if workers can’t get enough hours, and there are a number of efforts underway to pressure local and state governments, as well as employers, to improve conditions.

Eight states and the District of Columbia already have “reporting pay” laws. These require the employer to pay a minimum number of hours to workers even if they are sent home early. For example, New York State requires employers to pay a minimum of four hours per shift.

Perhaps the biggest victory in the US came last year in San Francisco. There, the county board of supervisors adopted a Retail Workers Bill of Rights that covers the city’s chain stores.

While only about 12 percent of retailers fall under the measure’s definition of a “formula retail” store, that 12 percent employs over 50 percent of all retail workers.

The Retail Workers Bill of Rights includes the following mandates:

Employers are required to pay two to four hours for workers for on-call shifts that do not materialize, or if they are sent home early before their scheduled shift ends.

Employees must get schedules at least two weeks in advance.

Employees receive extra pay for changing a schedule (one hour of pay for a change made with less than a week’s notice, and two to four hours pay for changes made with less than 24 hours’ notice).

Employers cannot pay different hourly rates for part-time workers versus full-time workers (unless there are other reasons, such as seniority).

Part-time workers must get the same treatment as full-time workers (such as the same access to benefits and vacation time).

Employers must first offer full-time work to existing part-time employees before hiring new temporary or part-time workers.

In addition, Vermont state law now grants employees the right to request flexible work schedules, and employers are required to consider it in good faith. The SeaTac and Los Angeles living-wage ordinances mandate that employers offer full-time work to existing part-time workers before hiring new employees.

Activists have also directly pressured employers to improve their practices. OUR Walmart called on the retailer to allow workers access to scheduling software. The company eventually acquiesced and agreed to let workers use the technology to pick up additional shifts of work. Just last month, Victoria’s Secret announced that it would end the practice of on-call scheduling after years of pressure from the Retail Action Project to raise pay and improve working conditions.

In New Zealand, the union Unite has been targeting fast-food companies to eliminate zero-hours contracts. They have won agreements from most, and when McDonald’s resisted, the union went on strike. McDonald’s caved, agreeing to end the practice and give workers a guaranteed minimum of hours.

In the UK, unions and worker organizations are trying to eliminate the zero-hours contracts via legislation. There has been a little progress — but not nearly enough.

The problems of too few hours and lack of schedule control will become more pronounced as the global labor force experiences greater precarity and more “flexibility.” Employers will likely keep pushing for more just-in-time scheduling as a way to convert labor from a fixed to a variable cost, from a formal employer–employee relationship with responsibilities to an informal one with no legal restrictions or promises of work.

As workers and worker organizations fight back, it’s a good time to think about the bigger picture of what we want. Certainly too few hours is a serious problem, but the solution is not necessarily more hours of work — or a return to a forty-hour workweek. The notion of flexibility has appeal because in reality, there are many employees who want or need an adjustable workweek — either to care for family, go to school, deal with a disability, pursue outside hobbies, or simply because working forty hours per week is too much.

Because of course, the flip side of not enough work is too much work: workers who are forced to work overtime, double-shifts, or two jobs because one doesn’t pay enough to live on.

The Obama administration just released new Department of Labor rules that would expand eligibility for overtime pay. The Fair Labor Standards Act currently exempts a large number of workers from the overtime provision: those who earn at least $23,660 per year in a range of professional and managerial occupations. So, for example, if a manager at a fast food restaurant makes $25,000, they’re not eligible for overtime pay, even if they work fifty or sixty hours per week. The new rule would raise the threshold to $50,440 per year. The revision is expected to impact almost 5 million workers in the first year of implementation.

Clearly, the labor market is out of balance, as some workers are working too much and others too little. The fight for schedule control should also be a fight to redistribute work hours and shorten the average workweek. This would help spread labor around more evenly, and should allow more space for workers to determine their shifts.

Anna Coote of the New Economics Foundation argues that we need a thirty-hour workweek because it “will help solve a lot of connected problems: overwork, unemployment, overconsumption, high carbon emissions, low well-being, entrenched inequalities and the lack of time to live sustainably, to care for each other and simply to enjoy life.” And research shows that a shorter workweek can actually increase productivity, which means that some of the costs of raising wages could be offset.

The International Labour Organization found that during the Great Recession, some countries experienced skyrocketing unemployment while others did not. Those that had lower unemployment were ones where countries introduced or encouraged shorter workhours rather than lay-offs. This policy, called Kurzabeit in Germany and work-sharing in others, offers benefits or incentives to employers who offer work-sharing and/or penalties to those who terminate employees.

Work-sharing policies also involve giving workers the right to request a shorter workweek, amending benefits to eliminate a minimum hours requirement, and increasing the minimum wage and social welfare benefits so that a shorter workweek is more affordable. Austria, Belgium, France, Japan, Turkey, and Uruguay are some of the other countries that have experimented with variations of shorter workhours and work-sharing.

The concept here is schedule control. But the schedules we choose are obviously heavily dependent on the wage we earn. So beyond schedules, workers want more voice in how to prioritize their demands. Not every worker will want the same thing and therefore the ideal is worker voice and organization, so that employees can debate and decide amongst themselves what they would like to demand from employers.

Ideally, we would have flexible jobs that allowed each of us some degree of choice over the hours we worked, the schedules we set, and the work we did. But this won’t happen through good human resource policy. Instead, we need democratic, worker-run workplaces.