The inconsistency in how battlefield upgrades are handled has been a MAJOR source of discomfort for DL frequent flyers. I think most of us would accept the protocol if only we knew what that was. For some GAs checked in full means boarded full. For some the list remains unchanged no matter who has already boarded, for others once you board you're off the list. I believe the official policy is that once you board you are off the list but application of this policy is so inconsistent who knows?? If I'm on the battlefield and have a good chance for victory I wait 'til the end to board.