I neven had two requests pending etc. Between 72 hours and 42 hours out my status went from waitlisted to denied. I thought this meant that I was not going to be able to get an upgrade at all. I think what happens is that when it says "denied", it means that you will have to wait till you get to the gate to find out. Basically, I am guessing that once they fill first/business to a certain point, everyone after that will go from waitlisted to denied until you get to the airport. Then the gate agent can release the rest of the seats just before takeoff.