@Gargron That's just not sustainable for more than a few months. I've done 1 or 2 death march programming projects in the distant past. My son also burned out trying to do too much teaching and research, and has had to take some years out to get his health back.

We're human beings, not human doings. 50 hours quality work in a week is more productive longer term than never switching off and doing other things, because you'll do more limited sessions in a better state of mind. Just say no.