really depends on the GA.....

i have seen GAs going down the upgrade list after announcing unsuccessful names

i also haver recieved UG boarding pass at the gate 30 mins before departure (during the calm of the storm)

i been asked to move up after seated

also been told if #4 does not arrive i will be #5 on the WL and its up to me to stand and wait or get on the plane + take the economy seat