With the unemployment rate lingering near a 50-year low, employers are competing hard to recruit and retain talent. Some companies are beefing up their perks by offering four-day workweeks to entice workers seeking a better work-life balance.

When businesses offer flexible schedules "we see an increase in productivity," said Bill Castellano, a professor at Rutgers' School of Management and Labor Relations. "It does have a positive impact on engagement. People who have flexibility feel reciprocity. They want to give back to the company."

There are different ways of delivering on the promise of a four-day workweek. Some companies have employees work 10-hour days, while others shorten the number of hours worked each week to 32. Some schedules involve eight nine-hour days and one eight-hour day, with every other Friday off.

Shake Shack recently announced it would test out the idea of a four-day workweek at some of its restaurants on the West Coast. The tests vary by restaurant, but employees work an average of 40 hours in four days with the same pay and benefits.

"The days of the restaurant business have been -- you work really hard, you're never home, you work six, seven days a week and 12 to 14 hour days," Shake Shack CEO Randy Garutti told CNN's Christine Romans in a recent interview. "Lately we started challenging that notion."

We are getting the same amount of work done, we are just being smarter about it. I am not asking people to do less" Nagele Nagele, Wildbit CEO and cofounder

Employees at software company Wildbit have been working 32-hour, four-day workweeks for more than two years. The shorter week started out as an experiment over one summer, but it proved to be beneficial for everyone.

"We continued to extend it each quarter and a year later when we reflected, we realized we had gotten more done that year than we had in a long time," said Natalie Nagele, the company's CEO and cofounder.

Getting an extra day provides employees time to regenerate, she added.

"By Monday morning, everyone is kind of running to work. You can process challenges and think through things you were blocked by and then by Monday you feel more empowered to get work done."

Losing a day of work made some employees anxious about maintaining their workloads, but the all-remote company learned how to be more efficient.

"We are getting the same amount of work done, we are just being smarter about it. I am not asking people to do less," said Nagele. Employees are limited to two 30-minute team meetings each week. "The rest of the week should be meeting-less to make sure days are purposeful. They are in control of their own schedule."

For her own schedule, Nagele doesn't take meetings on Wednesdays. "It's my day of no disruptions, I can sit quietly and work."

The company continues to look for ways to boost productivity. Employees spent this month tracking their work schedules to see how much uninterrupted "focused time" they get and to identify any distractions.

"We are looking at our days to see what we can do to maximize what work we can get done," Nagele said.

The key to making a four-day workweek sustainable is setting very clear and measurable goals, according to Castellano.

"Free Fridays" was part of the deal when the founders of Cockroach Labs in New York City launched their computer software company in 2015. Giving employees more flexibility in their schedules fits two of the company's values: balance and respect.

"Burnout is real," said Lindsay Grenawalt, chief people officer at Cockroach Labs. "When you hire brilliant people, they will give everything to your business. It's on the business to say, 'hold on, we don't want you to burn out. We want you here for the long haul and to do your best work.' You can't do that if you are exhausted and angry."

She remembers scoffing when she learned the company had a four-day workweek -- and she wasn't even working there yet. "I remember saying to the [CEO], 'that will never scale.'"

But it has -- with some changes -- over the years.

The company changed the name to "Flexible Fridays" as it grew and had to accommodate customers and other partners who were still working five-day weeks.

For instance, perpetual three-day weekends didn't work for the sales department.

"They have to be available to hit the goals," said Grenawalt. The sales department does not get Fridays off, but is offered commission and bonuses that are not offered to other departments.

Managers set clear goals and objectives that are reviewed every quarter and they have a weekly team meeting to evaluate objectives and key results to ensure progress.

To help curb distractions, employees are given noise-canceling headphones and some engineers have a light on their monitors that signals when they are open to conversations.

"Our employees are very engaged and appreciative of the business," Grenawalt said, adding that the company conducts biannual engagement surveys. "If you want to attract and hire the best people, but don't respect them, they will go somewhere else. There are too many options out there."