No, I think you're right. I used to do real slow acclimations with BTA's, and have never seen any difference between those and a 1-1.5 hour acclimation. But then I usually test the water the anenome is in, pH, Alk, etc and shorten the closer it is to that of my tank.
Within reason of course, if you were stuck in a small tank with 02 really low, and lots of waste in the air, why exactly does keeping you there for 2-3 hours additional help? Unless there is a big temp or pH difference.