The theory behind introducing a four-day work week—without cutting pay—is that employees will be so delighted to have time gifted back to them that they’ll work harder in the hours remaining. The latest trial to emerge, from the large workforce at Microsoft Japan, suggests it might be applicable at scale, and even in one of the world’s most notoriously “workaholic” cultures.

Microsoft Japan ran a trial in August 2019, when every Friday it closed the office and gave roughly 2,300 full-time employees a paid holiday, according to Sora News 24, which first reported the story in English. The result was an enormous jump in productivity. Based on sales per employee, workers were almost 40% more productive in the compressed hours of August 2019 as they were the same month a year earlier.

Other productivity hacks were also encouraged, including limiting meetings to 30 minutes and suggesting that instead of calling meetings at all, employees could more fully utilize software available for online collaboration (in this case, of course, that software was Microsoft Teams, though other systems are available). On their day off, workers were encouraged to make use of the time by volunteering, learning, and taking rest “to further improve productivity and creativity,” according to a company blog (link in Japanese).

In the coming months, another trial will run with slightly different parameters, the blog adds. This trial won’t cut hours in the same way, but rather suggests that employees focus on resting well and coming together to share ideas about how to work, rest, and learn.

Other companies that have trialed and implemented four-day weeks have found, similarly, that their productivity is boosted. Perpetual Guardian, the New Zealand estate management firm that was one of the first to go public with a research-backed assessment of its trial, and then adopted the policy in November 2018, found that productivity was unharmed by the shortened work week, while staff stress levels were dramatically improved. More recently, recruitment firm ICE Group this year became the first company in Ireland to adopt a four-day week for all its staff.

Microsoft Japan’s trial is significant because it’s the biggest yet in terms of both staff numbers and the apparent effect on productivity. It’s caught the global imagination, perhaps, because Japan’s work culture is seen as particularly punishing. If a big Japanese tech company can change its ways and achieve startlingly better results, perhaps there’s hope for combatting other long-hours work cultures, like the US.

With translation assistance from Tatsuya Oiwa.