Refreshed, on top of personal life stuff, and ready to go. Why do we work 5 on, 2 off? How did that naturally become the standard.
I'd argue that if our economy did a rolling 5 on, 3 off for everyone the whole output would net MORE productivity overall
It didn’t. People fought and died for this and many other protections, engaged in massive disruptions of their workplaces and society at large. If history and the developing world are at all examples, businesses would rather work people to death and use every form of coercion possible to drive down the price of labor.
The degree to which we forget that this and are unwilling to do the same is the degree to which these rights will be eroded.
If you work for a western company or have a skilled white collar type job you work either 5-2 or 5½-1½. That is, you work a half day every Saturday. It is so common that every commercial lease I've seen covers it. e.g. "we provide air conditioning from 8am-6pm Monday to Friday and 8am-1pm on Saturday".
Everyone else -- which is probably 90% of the country -- works 6 days a week. That is, they only get 1 day a week off. 4 days a month. (And it is common for people to work 10 hour shifts.)
As you say, 5-2 only became the standard because originally it was 7-0, which then became 6-1, which then became 5-2. Each of those transitions took decades. In Australia, the 5-2 work week didn't become a thing until 1948. It took a 2 year court case to change from a 6-1 schedule to a 5-2 schedule. At the time employers said, "Australia is committed to an unnecessary and dangerous experiment".
Hong Kong only implemented the 5-2 schedule for government workers in 2006. Before that, they were expected to work on Saturdays.
In Saudi Arabia, I believe that government workers still work 6-1 schedules.