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Most of the companies that took part in the world's largest four-day week trial will continue with the experiment. 

Some 61 companies with around 2,900 workers joined the six-month trial. Now that it's over, 56 companies have opted to extend the four-day week -- and 18 of these firms have made the change permanent. 

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Participating companies from different sectors tried different four-day models, including 'Friday off', 'staggered', 'decentralized', 'annualized', and 'conditional'. Staff maintained their existing salary, but worked across four days instead of five.

The trial, which took place from June to December 2022, involved two months of preparation, workshops, coaching, mentoring, and peer support.   

The study found that 39% of employees were less stressed after the trial, and 71% had reduced levels of burnout at the end of the trial. Some 54% reported it was easier to balance work with household jobs while 60% found it simpler to combine paid work with care responsibilities, and 62% reported it was easier to combine work with social life. Companies reported a 57% fall in staff departures over the trial period. 

The trial was headed up by 4 Day Week Campaign, backed by think tank Autonomy and researchers at Boston College and the universities of Cambridge and Oxford.

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"This is a major breakthrough moment for the movement towards a four-day working week," said Joe Ryle, director of the 4 Day Week Campaign. 

"Across a wide variety of different sectors of the economy, these incredible results show that the four-day week with no loss of pay really works."

The report's authors note the trial took place with organizations that selected themselves, making it more likely they would make it work, but they also argue the results do support a shorter working week.

"We don't have a firm handle on exactly what happened to productivity, but we do know that on a variety of other metrics, whether we're talking about revenue, [workforce] attrition, self-reports of productivity, employee well-being and costs, we had really good results," said Juliet Schor, from Boston College, according to BBC.

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