I wonder what a plausible model for productivity by hours work is, and whether it varies by occupation.<p>Especially for piecemeal labor, after getting to the point where you maintain your baseline level of skill (say, 10 hours/week?), it seems like each marginal hour will have less productivity than the previous. It probably never drops to negative, unless we're talking 80 hour weeks.<p>It's less clear to me that the same is true of so-called knowledge workers. Or, at least, the baseline is much higher. My bet would be that an engineer who only works 10 hours/week is going to be less productive, on an hourly basis, than one who works 20 hours/week. I'm not sure what the inflection point would be, though.<p>I think a better model would be having a year or two of relatively long workweeks (40 hours a week) to be followed by a year or two of vacation and education, instead of 20 hours/week consistently.<p>Another approach would be decreasing the retirement age. I'm less a fan of this, as too many people end up depressed and lost after they leave the workforce. Plus, it's a raw deal for people who die before they retire.