Really curious to see how this plays out given a lot of turns (particularly later in the day) are tight to begin with / schedules are designed to absorb delays. This will likely result in a lot of passengers putzing around the gate at T-40 asking why the plane hasn’t started boarding (already happens enough as-is!).

As others noted, Delta likes doing this. It is never enjoyable to start boarding a 6 am departure on a E175 at 5:20 am or be told by rolling up at 5:35ish that they are in final call / were planning to depart early . This has at least been DL’s approach to the “shuttle” flights. Ideally AA won’t apply this to the 175s as the 25 minute boarding is generally sufficient.