[CookWithMe]

And what about Company C that puts in 80 hours? And Company D that puts in 100 hours?

The math adds up, at least up to the point when it hits 168 hours ;)

This is really the wrong model. There is a sweet spot of hours vs. productivity somewhere, it's probably different for everyone. I guess for me it is even changing on a daily basis. Some weeks I can work through the night or on the weekend, othertimes I can't seem to get stuff done and be exhausted on a wednesday...

[atspcohn]

80 hours/wk or 100 hours/wk are extreme hours that i wouldn't or didn't advocate.

[eli_gottlieb]

The real question is of marginal productivity-per-hour. We know that work-hours have a diminishing-returns point passed somewhere around 30-50 (depending on the person and the occupation and the match between them). I think of it this way: if you really need to work more hours to get more done, only keep doing it as long as your productivity-per-hour stays the same. That's the point where you're making a zero-sum trade of more hours for more stuff done.

However, there's also another really important aspect! If you only ever focus on working harder, anyone who works smarter can come along and beat you while working less than you. Beating them through sheer work-ethic will easily push you into negative returns-per-hour, destroying you and your business through sheer desperation.

For example, anyone with a source-control tool will be several times more productive in software engineering than someone who didn't use one and has to manually revert his changes. Remember, this used to actually happen.

So when you're working hard overtime, watch your back! You could be competing against someone cleverer than yourself.