I don't think human production is linear. There's definitely an optimal point, and it probably varies from person to person. I think, actually, past that point

I don't think human production is linear. There's definitely an optimal point, and it probably varies from person to person. I think, actually, past that point your productivity declines rapidly. I would not be surprised at all if working 70 hours a week yields more productivity than 80, which yields more than 100.