Based on the responses, either I've been unlucky, or maybe I just haven't noticed miles posting same day of flight, because I haven't looked at my account very often the same day. I've been in the habit of looking the next day to see if they'd posted correctly. It's possible I have had some post the same day, and just didn't realize they had.

Considering I'm still waiting 3-4 days for Bonvoy points to post, I consider this a big win for AA and their dinosaur of an IT system. Not that I ever need to immediately turn around and use the miles I just earned, but it's nice to see them post and check them off the pending list.