I can only share my experience from my home airport (ALB) but US has been monkeying around with the schedule, especially the early morning flights. The 5:30 flight to DCA has varied between 5:30 and 6:30 and the 5:30 flight to PHL was recently removed altogether, killing the entire first bank of connections one could have made in PHL. Extremely inconvenient as connections at DCA are limited and the first CLT flight is too late for useful morning connections.
It looks like starting in March they're getting rid of much of the daily variability in the schedule and going to mostly flights that operate 7x/week instead. Doesnt much help if I can't reliably get anywhere before noon using those flights unless I leave the day before.