Most people going to Skywest have the same thought process. Get in, upgrade, move on to whoever calls first. This creates a lot of movement within the company. There is no real loyalty and almost all of the people I fly with have apps out to all the majors, fedex ups and Southwest. A lot also have apps at the low cost carriers too.
People who go to the American regionals primarily have only going to AA on their minds and sometimes to their own detriment. In other words, they will wait until flowing to AA instead of trying to get on elsewhere. It’s somewhat similar to endeavor and delta. They have getting to delta their main goal and will usually hold out applying at other places until their guaranteed interview comes. Problem is their interview is only after 18 months as captain and their upgrade is at a trickle right now. This can slow attrition at places like these as a lot of people choose to stay in line instead of bailing elsewhere.
Skywest is far from perfect, but has a quick upgrade, good selection of bases, and a lot of attrition. Upward movement has come quickly and seniority in the junior bases moves fast.