When New Zealand financial services company Perpetual Guardian began a trial of a four-day working week early last year, many employers and policymakers watched with interest.

Sure, the idea sounds good, but does it work?

Under the eight-week trial, Perpetual Guardian switched its 240 staff from a five-day to a four-day week and maintained their pay.

The results were promising enough that in November last year management gave staff the choice to opt into the policy and work 30 hours instead of 37.5.

Unsurprisingly, it was a popular move.

The experiment was monitored by academics at the University of Auckland and Auckland University of Technology.

Their research, published this week, found productivity increased in the four days worked by 20 per cent, so there was no drop in the total amount of work done.

Staff wellbeing and satisfaction pre-trial and post-trial Stress levels: Down from 45 per cent to 38 per cent

Work-life balance: Up from 54 per cent to 78 per cent

Leadership: Up from 64 per cent to 82 per cent

Commitment: Up from 68 per cent to 88 per cent

Stimulation: Up from 66 per cent to 84 per cent

Empowerment: Up from 68 per cent to 86 per cent

It also found that - compared to a staff survey in 2017 - employees felt less stressed and more simulated, empowered and committed.

In other words, staff were more productive and apparently happier.

"[Employees] spoke of the need to 'have each other's backs' in order to make the new policy work," University of Auckland's Dr Helen Delaney said.

"Many employees also spoke of increased levels of intellectual stimulation and creativity during the trial.

"A number of employees said the trial had helped increase their confidence and help them have more say over how they worked.

"Some felt more confident about making decisions and being proactive - a sentiment echoed by management."

Australians work long hours, but how much is productive?

Australians are currently working long hours, and many want to work fewer.

Although the mean weekly hours has fallen since 2002, that's partly due to the increase in underemployment. Australia ranks ninth among OECD nations (most of the developed countries in the world) for its share of long-hour workers - people who usually work more than 50 hours each week.

A 2015 national survey found 26 per cent of all employed persons would prefer to work fewer hours (and 16 per cent would prefer to work more).

Despite the long hours, the time spent working may not be so high.

A 2017 UK study found the average time spent working is two hours and 53 minutes each day, with the rest going to social media, news websites, non-work chats with co-workers, taking meal and drinks breaks, going out for a smoke, and searching for new jobs.

Almost 80 per cent said they were not productive throughout the entire working day and over half said distractions made the working day "more bearable".

In the 2018 book Bullshit Jobs, anthropologist David Graeber contends the reason the productivity benefits of automation have not led to a 15-hour work week - as predicted by economists in 1930 - is due to the rise of pointless work in services industries.

"More and more employees find themselves ... working 40 or even 50 hour weeks on paper, but effectively working 15 hours just as [John Maynard Keynes] predicted," he wrote.

The rest of their time is spent organizing or attending motivational seminars, updating their Facebook profiles or downloading TV box-sets.

Since the 1950s, the idea of diminishing productivity has been known as Parkinson's Law, which is that "work expands so as to fill the time available for its completion".

A 2015 survey by UK market research company YouGov appears to support this; 37 per cent of British workers think their jobs are meaningless.

Staff at Perpetual Guardian reported that when the working week was shorter, everyone became more conscious of not wasting time.

The company's CEO, Andrew Barnes, has called on other corporate bosses to follow his lead, saying the four-day week is "an idea whose time has come".

The NZ company says it has received 350 requests from 28 countries, including Australia, for its how-to-guide for making the switch to shorter hours.

The UK's Wellcome Trust, the world's second-largest research donor, has announced it is considering a trial that will see all 800 head office staff moving to a four-day week.