"The eight-hour workday is not based on the optimal number of hours a human can concentrate. In fact, it has almost nothing to do with the kind of work most people do now: Its origins lie in the Industrial Revolution, not the Information Age." [0]
"Would you like to have 4 hours workdays? That's the question really. We know that we're spending less than 40% of our workday actually working, but would you be willing to sacrifice what you do on that extra 60% just to end your day sooner? [1]"
"The 8-hour workday has been the norm for more than a century, but employee surveys suggest that most people are truly productive only for about three hours every day. This has led to calls for the workday to be reduced to five or six hours, with proponents saying it would increase employee wellbeing, and ultimately productivity." [2]
"Mexico—the least productive of the 38 countries listed in 2015 data from the Organization for Economic Cooperation and Development (OECD)—has the world’s longest average work week at 41.2 hours (including full-time and part-time workers). At the other end of the spectrum, Luxembourg, the most productive country, has an average workweek of just 29 hours." [3]
[0] https://www.inc.com/melanie-curtin/in-an-8-hour-day-the-aver...
[1] https://freedium.cfd/https://medium.com/varietate/the-9-to-5...
[2] https://www.seattletimes.com/explore/careers/clinging-to-an-...