I've had jobs with 70-80 hour weeks I genuinely loved, and jobs that required maybe 4-8 hours a week of actual time devoted to it that burnt me out. Burnout is a lot more complicated than the sheer number of hours worked - if you are deriving meaningful value from such a schedule, and feel what you are doing is worthwhile, and you feel valued and compensated accordingly - you're not likely to mind that much. The issue of course is that this is rarely the case, and plenty of studies have shown there are severe diminishing returns to working past 50 hours in a week in knowledge work that I doubt AI is going to really help with that much.