At some startups, Friday is so casual that it’s not even a workday
The stories vary in quality and details, but as far as we can tell the 40 hour week was implemented by Henry Ford in 1926, after careful record keeping and analysis revealed that the ratio of worker output per week to wages paid per week peaked at about 40 hours per week of work.Now, that's fine for factory work, but as far as I know, relatively little effort has been put into testing that theory in knowledge jobs.