Worked great for me...saved my butt plenty of times at school - though I got worse at procrastinating, since I figured, "Ah, a couple hours is plenty of time to read that."
Which it was, but eventually I gave myself less and less time, and the next thing you know, I just stopped doing work altogether.
First semester = Just got PRing; started great, became irresponsible, went Down down down...
Second semester = got more control over myself, used PRing responsibly, went up up up.
It works, just be responsible with it.
-Ramon http://razor.ramon.com