Yes, over the course of a 12 year full time career, if I go above 55 it gets worse, but I can sustain 55. In terms of trade offs, there's something to be said for parkinson's law. If I have way more than 55 hours a week of stuff, I know I have to fit it into 55 or I'll burn out. If I aim for less, I find I never end up working less than 40, even if the absolute amount is much lower.