4-day work week trials in Iceland deemed 'overwhelming success' by researchers By Kelly Hayes Microsoft Japan boosted productivity by 40 percent by switching to a four-day work week Compared to a year prior, sales per employee in August 2019 were found to be 40 percent higher, while total working days were down 25.4 percent. Trials of a four-day work week held in Iceland were deemed an "overwhelming success" by researchers in a new report. Iceland conducted two large-scale trials involving over 2,500 workers, which is about 1% of Iceland's entire working-age population. Participants were from a wide range of workplaces, including offices, hospitals, schools and social service providers. Participants in the trials worked 35-36 hours per week with no cut in pay.