The main reason staff are left on standby till the last minute ex LAX, is the high fuel uplift required for the sector back to Australia. There shouldn't be any reason that you don't know if you're on or not at 30 mins before departure. The reason for this is that the flight closes at -30mins, so all the no-shows are known then and that is also when the upgrades should be done for those that don't yet have them.
Having said all that LAX is the worst I've experienced. HKG was the best. I thought I would ask at the train station on HKG Island if I could check in there, and I let them know I was staff. Not only was it ok, but got my upgrade and choice of seats in J class, and it was reasonably full. HKG was great, but arrival in MEL was shocking took a good hour and a bit to clear Customs and collect bag. Lucky AQIS didn't want to x-ray my stuff.