Promotions within a company are based on ranking employees. Even if not done explicitly, you still promote your top people. Working more hours is a way to incr

Promotions within a company are based on ranking employees. Even if not done explicitly, you still promote your top people. Working more hours is a way to increase your rank. Thus it becomes an arms race between the employees. You work 40 hours, I increase to 45, then you increase to 50. So, to some extent, hours worked don't correspond to hours needed to be worked for productivity purposes.