This. I spent 2 years sleeping 4:30hs on weekdays (a combination of college and full time work). But then I would sleep 10h+ hours per night on weekends, was constantly tired, and Mondays were always terrible days as I adjusted back.

It was "doable" in the sense that I didn't sleepwalk into traffic, but in the end my performance both at work and at school was terrible. It was a waste.

It's somewhat fine if you're doing rote work, which I assume these people are doing, but little else.