The most I've worked in my life was a two week intensive effort to reach a deadline. I did little more than work eat and sleep, and yet I only worked 75 and 80 hours. And my brain was pretty fried after. This was working from home, with rewarding work I was motivated to do. I don't see how it would be possible to work 95 hours in some office, let alone the 105 hours reported with 5 hours of sleep. It wouldn't make any sense. If you haven't slept more than 5 hours, the other 15 hours (assuming you work Saturday and Sunday) are going to be unproductive. Diminishing returns is a real thing. So, the managers here seems both very unprofessional, and remarkably bad. No one wins, and everyone loses? Nice way to run a business.

If you're working 105 hours, you don't have time for HN.

I did 80's (over 5 days) for an extended period of time twice and you definitely adjust.

Looking back, the quality of work was definitely diminished. It didn't impact me too greatly in the first because it was a sales role primarily filling out RFPs. The second time was my startup and I am confident I made plenty of bad decisions due to lack of relaxation/sleep/exercise.