3 day work weeks happen, granted, they’re 12hr shifts.
That said, they’re not a feasible setup for anyone human unless there is “block” scheduling. Meaning the 3 days are clumped together 90% of the time. 3 on, 4 off. Some variation, meaning you have 5 or 6 days off on occasion.
Even so, society didn’t collapse when these 36hr weeks were implemented. I’m almost positive rolling it back another 4 hrs for the 8hr workday set wont either.
My understanding is some manufacturing forces 4 twelves every other week rather than hiring 1 more person and being creative with schedules. IMO forced OT on twelves is an awful practice and not life balance sustainable.