A few years ago (2014ish) I would start the work week pulling 7am to 10:30pm - approx 15 hour days -- but couldn't sustain that for more than a couple of days,

A few years ago (2014ish) I would start the work week pulling 7am to 10:30pm - approx 15 hour days -- but couldn't sustain that for more than a couple of days, so by Friday my hours would drop to 10-11 hours per day, and I would spend pretty much the entire weekend asleep - so significantly less than the 90h claimed and much closer to 60h. After a couple of years of this, I was in the middle of an emotional breakdown with rapidly encroaching early-onset rheumatoid arthritis - my body couldn't handle it any more. So ... while I don't think it's totally impossible - it's also a long way from being a healthy lifestyle. (Needless to say I try to avoid this sort of thing these days).