>I can pretty easily do 16+ hour days if I'm doing something I enjoy But is there context switching? I can probably do 12hrs of X, but if it's 8hrs of X + 4hr

>I can pretty easily do 16+ hour days if I'm doing something I enjoy But is there context switching? I can probably do 12hrs of X, but if it's 8hrs of X + 4hrs of Y, X and Y being things I enjoy and want to do very much, I don't think I'd have the wherewithal to switch to Y after 8hrs of X. 12 hrs of X: you're already in the groove, you have the context, you're working toward a goal in a continuum. 4hrs of Y, you have to spend activation energy, fiddle a bit with finding where you left off, what the problem space was, before you get in the groove. That take-off alone will sap probably an hour. You can do it, but attended with all our human foibles, are you going to mentally decide you're going to start Y, after 8hrs of X?