Originally Posted by
jpezaris
As just one observation, you implied that a given airfame operates back-and-forth between a hub an an outstation. I don't have a handle on what fraction do that, but I rarely see that pattern. Instead, I see flights go from one hub to an outstation and from there to a different hub, so suspect that your hypothesized two hours of idle time at the outstation is where efficiency gains have already been found.
Maybe on UA that happens more, but it definitely does not happen that much on AA and DL. Actually, the outbound from the hub and the inbound back to the same hub with the same aircraft, more often than not, use the same call sign.