Originally Posted by
pitz
Of course, nothing stops someone from redeeming a J reward, for a later flight, showing up early, and going standby. The standby list clears before the upgrade list.
I really don't want to disagree with you over more upgrade/standby stuff, but I can assure you, upgrades clear before standby.
And I say this having been an SE booked in full J who was offered 18E, while a P25K on some random fare was given a ML*1 boarding pass for 1D.
The theory behind this is that people already confirmed on the flight have priority for J over those who are not confirmed on the flight, presumably to prevent exactly what you're suggesting.
The unfortunate side effect is that flexible fares aren't very flexible close to departure.