The supermarket chain launched a trial to see employees work their 44-hour week over four days instead of five for the same pay. That translated into 11-hour shift patterns for labor-intensive work.

Inevitably, the idea of fulfilling the same weekly hours in a shorter timespan had adverse consequences for Asda employees. Staff described the shifts as “physically demanding,” while the early starts and late finishes left those depending on public transport in a bind.

Parents who work at Asda also faced issues coordinating childcare and school pick-ups and drop-offs under the 11-hour shifts.

The group decided not to continue with the condensed four-day workweek, but is trialing a flexible 39-hour week over five days.

“We will continue to test different flexible working patterns to assess how these can benefit our colleagues and our business,” a spokesperson for Asda told Fortune.

Asda isn’t the only company that has faced fitness issues from staff after trying to introduce a condensed working pattern. 

The insurance company Domestic & General introduced a similar condensed working week but also faced complaints from staff who were left psychologically exhausted.

“Half the team absolutely loved it, half of the team didn’t like it at all—it makes for a longer day, it’s a bit more intense,” Crummack told The Telegraph. “For them, spreading the work across five was easier to manage psychologically,” 

Last year, Crummack told Bloomberg that companies implementing a four-day week tend to lose “flexibility” and inevitably force workers to pick up extra work on the fifth day anyway.

How to successfully bring in a 4-day week

Asda’s and D&G’s announcements came just days before South Cambridgeshire council hailed the resounding success of its four-day week trial.

The council’s 450 employees carried out the biggest-ever public sector trial of a four-day workweek.

Among the benefits was a 39% reduction in staff turnover, which helped save the council £371,500 ($476,000), thanks to lower staff agency costs, The Guardian reported.

At the same time, the council said it processed 15% more major planning applications, while household planning applications were completed a week and a half earlier, indicating a huge productivity boost.

“We know we cannot compete on salary alone and have needed to find bold new ways of tackling our recruitment and retention issues,” John Williams, the lead South Cambridgeshire council member for resources, told The Guardian.

Four-day week trials have increased in recent years, with varying results showing success isn’t guaranteed.

The most successful trials tend to see employees shorten their hours for the same pay, as with South Cambridgeshire Council. 

A four-day week trial saw more than 60 companies and nearly 3,000 employees in the U.K. experiment with the 100:80:100 model, where staffers received 100% of their pay for 80% of their time while delivering 100% productivity. 

A year after the trial’s completion, Autonomy found that 89% of companies were still implementing a four-day week after employees saw burnout drop significantly and employers enjoyed a fall in attrition.

However, the latest results from Asda and D&G suggest that the benefits of an extra day off are canceled out if employers try to make their employees work the same number of hours in fewer days.

While U.K. companies and public organizations experiment with increasing their employees’ leisure time, Greece is taking the opposite approach in search of productivity gains. 

The country has relaxed labor laws in some industries, allowing companies to hire workers who work 48-hour weeks.