4 day week
“The five-day, 40-hour work week was well and truly entrenched in the 20th century. Previously, the industrial revolution resulted in work dominating life to such an unhealthy extent it wasn’t unusual for people to work 16 hours a day, six days a week. Across the late 1800s demand for better regulation of work hours ultimately culminated in US federal laws setting the maximum work week at 40 hours, with overtime for hours worked beyond that threshold.”

https://newatlas.com/health-wellbeing/iceland-short-hours-4day-work-week-trial