The four-day workweek is proving to be the gift that keeps on giving.

Companies that have tried it are reporting happier workers, lower turnover and greater efficiency. Now, there's evidence that those effects are long lasting.

The latest data come from a trial in the U.K. In 2022, 61 companies moved their employees to a four-day workweek with no reduction in pay.

They began it as a six-month experiment. But today, 54 of the companies still have the policy. Just over half have declared it permanent, according to researchers with the think tank Autonomy, who organized the trial along with the groups 4-Day Week Campaign and 4 Day Week Global.

Follow-up surveys help to explain the four-day workweek's success.

Improvements in physical and mental health, work-life balance, and general life satisfaction, as well as reductions in burnout, have been maintained over the past year, says sociologist Juliet Schor of Boston College, who's part of the research team. Workers report higher job satisfaction now than before the trial began.

"The results are really stable. It's not a novelty effect," she says. "People are feeling really on top of their work with this new model."

Similarly positive results are emerging from other four-day workweek trials, including in the U.S., Schor says.

"Doesn't happen by magic"

At a recent webinar, participating companies shared their experiences and tips for success.

"It absolutely doesn't happen by magic," says Nicci Russell, CEO of the London-based water conservancy non-profit Waterwise. "You can't just drop a day and carry on as usual, because how stressful would that be?"

Russell says after some initial teething problems, they managed to find efficiencies that allow all 10 employees to take Fridays off. They keep all meetings to 30 minutes and make sure those meetings start on time. They block off focus time on their calendars — sometimes even declaring Monk Mode Mondays. They're more mindful of the emails they send and of the time they spend going through their inboxes.

"I only do my emails now at certain times of the day. I'm not drawn into them all day, every day," she says.

At the end of the pilot, the staff at Waterwise were unanimous in their desire to continue the four-day week. A majority said they wouldn't consider a five-day-a-week job again unless presented with a significant pay raise.

"It's brilliant for retention, which is super important in a teeny organization like ours," says Russell.

No one-size-fits-all

One important finding, researchers say, is that there is no one-size-fits-all recipe when it comes to the four-day workweek.

At Merthyr Valleys Homes in South Wales, giving everyone Fridays off wouldn't have worked, says Ruth Llewellyn, who led the pilot at the housing cooperative.

With 240 employees working in roles from customer service to home repairs and maintenance, they decided to keep their operations running from Monday through Friday.

"For us, the thought of dropping repair service for our tenants one day a week meant that we wouldn't be providing the same service," Llewellyn says.

Instead, employees work a variety of schedules depending on individual and team needs. Some have a set day off every week, while others are on a rolling schedule. Some employees work two half-days, and some still work five days a week but shorter hours, allowing them to drop off and pick up their children from school.

The teams found time savings in different places. Some of the trades staff found they could reduce travel time to and from the building supplier with better planning around which materials they needed. Customer-facing teams found they could address smaller issues quickly over the phone.

Employees are more motivated, employee performance has held consistent, and absences for illnesses have fallen, Llewellyn says.

Yet the company is not committing to the four-day workweek forever — at least, not yet. Hoping for still more data, it extended the pilot and will re-evaluate the results later this spring.

"We're really hopeful at that point that we can make it permanent," says Llewellyn.

Why companies fail

Of the 61 U.K. companies that joined the 2022 pilot, only a few have discontinued the four-day workweek.

At one small consultancy, although the staff reported improved morale and the company reported a boost in efficiency, there were problems managing client and stakeholder expectations, according to feedback collected after the pilot.

Researchers suggest that better external communications and more flexibility in adapting the policy to challenging conditions might have made a difference.

"There is a suggestion that the organisation did not give the policy enough of a chance, and indications of a change of heart on the issue from management," the researchers wrote.