Currently I'm kind of in the middle of writing a research proposal due at 10 AM (in 5 hours). Not doubting I'll get it done in time, but I can't ever seem to get myself motivated until I look at the clock and realize "Crap, I should have started working on this days ago!"
Personally, the worst it's ever gotten for me was starting an essay at 2 AM and finishing at 7 AM the morning it was due, including the time spent to read the entire text. It was a fairly short play (The Importance of Being Earnest). Got an A+ on that paper, and usually get great grades on every paper I write that way. The few occasions where I've starting writing gradually a week ahead of time like I imagine most normal people do, I've gotten fairly poor grades.