Like everything else in life you need balance. Putting in hundreds of hours is really not that more productive than putting in 50-60. You may think you are doing yourself a favor by working such long hours, but in reality you aren't.

At a certain point any additional "work" you do is non-productive, when you are tired, your mind will start to wander, and you'll start making mistakes. And then you'll spend all that time you "saved" fixing them.