Because if you're trying to write and you have unlimited time, you can procrastinate an unlimited account, but if you have limited time, you rush to the page trying to get something down in the little bit of fragment of time that you have, and you may write a great deal that way.
“Intellectual despair results in neither weakness nor dreams, but in violence. It is only a matter of knowing how to give vent to one's rage; whether one only wants to wander like madmen around prisons, or whether one wants to overturn them.”