Not saying it is worthless, and yes, some people who would not otherwise EVER make it to the majors might make it because of flow. But hasn’t AA limited it to a max of 15 pilots a month? And I thought Envoy had about 2500 people on their own seniority list, so what the newbie deciding on a regional is actually looking at is this:

Over the last 10 years AA hiring has averaged about 250 a year. Right now they are over staffed by 300 pilots even with 1500 on furlough due to their aircraft fleet consolidation. With age related retirements, let’s say they boost that number up to recalling 750 furloughed pilots a year if international flying recovers as quickly as domestic flying (which it likely won’t) that’s still two years and four months before the FIRST guy can flow. So starting in March of 2023 the first of the 2500 people ahead of a new hire will flow, and assuming there is continuous hiring EVERY MONTH that will be 180 flowing a year. Now even if 700 people ahead of him/her either don’t ever flow (too senior and old to give up QOL at the regional to sit reserve FO at AA) or get selected to go to a major outside of the flow, that’s still ten years - March of 2033, before the newbie at a WO can expect to flow.

Now if for geographic reasons it makes sense for someone to choose an AA wholly owned over another regional they ought to do that - not because of flow, but because commuting is a pain, commuting to reserve is especially a pain, and commuting to a regional is particularly bad. But choosing a regional because of flow? Right now you are looking at 10-12 years. If you have no college degree and no intention of getting one, or have a spotty training record or mishap history that would make it unlikely you would get an offer from a major any other way...well, maybe flow would be more of an inducement.

But for Joe Average guy breaking in to the 121 world? I don’t see it being a serious factor.