You pretty much have to get lucky enough to have someone give up their seats while you're there to improve your seats if you already have fairly good ones. Otherwise, they get snapped up too quickly because of lack of availability.
So you could get there in an early session if you have a lot of points but easily have nothing available early but have someone late decide to upgrade, so someone with a later appointment could get lucky. Luck of the draw, like someone lucky enough to pull up just as someone's backing out of a parking space while someone else has been circling the block for 15 minutes but isn't at that spot at the right time like you were.
