That's exactly what has been found, as cited on another comment in this discussion:
http://www.lostgarden.com/2008/09/rules-of-productivity-pres...
The cited research claims total overall productivity of working 60 hours a week starts showing a deficit to working 40 hour weeks, after about 4 weeks.
Programming in particular has negative effects after the point of being tired. You make mistakes, you commit bad code, you have to maintain bad code for the lifetime of hte product.
That one grind where you kept pushing could keep affecting the productivity of the whole engineering team for the next 2 or 3 years. I've seen it happen. A lot.
I would assume doing strategizing or negotiating when tired could equally have devastating long-term effects on the business side.
Work as long as you want, just don't work tired. It isn't worth it.
Re:The Post-YC Slump
by cynicalkane on Thursday August 20, 2015 @02:35PM
(#10093739)
The diminishing returns affect all future hours, not the marginal hour. If you're tired all of your work will suck until you recover. That marginal hour might damage your ability to work more than the gain from working that one hour.
Sure, but I don't think there have been any studies that find negative returns after 40-50 hours.
If we are optimizing for maximum returns, rather than maximal efficiency, you would advocate for increasing hours worked until the result of one hour of work was zero.
Many activities have diminishing returns after a certain amount of work (oil drilling, distance running, mining bitcoin, etc.), but it doesn't mean that the rational decision is to stop when the point of diminishing returns is reached.