Beautiful weekend in September a few years ago was it, or close to it, with 1050 over the ridge. Including 46 coming down the OBP after dark (all parties had lighting, somewhat surprisingly). Only one search and rescue on that side of the notch (and another on the other side, in quick succession).
I'd thought about the Loop but given the number of cars went right on to the Ammy-Jewell loop. Quite a bit quieter!