So allow me to be the malcontent around here. I get these "instant" upgrades fairly regularly...and they cause me a fair bit of headache, cause they're too fast! I'll book something in Concur, or occasionally on the phone with AMEX Business Travel, and the upgrade will clear before the agency gets it ticketed...and that will hang the whole thing. It won't ever ticket unless I call back into AMEX and have them cancel and rebook it. On two occasions I showed up at the airport and walked up to security while working my phone to get a boarding pass, only to see there wasn't one because I never got ticketed because an upgrade broke everything. Nowadays I always go look at the AA website about 15 min after booking just to make sure it got ticketed.
One of those things...sure seems silly to be here whining about how fast I get upgraded. But man if they could just dial it back so upgrades clear 30 min after booking instead of immediately it would be a big improvement.