It is a fact of life when you are a hub and spoke carrier. You need to give people time to connect. You could try to depeak the hubs and go to a rolling hub concept as they have done with American in ORD and DFW, however, only PHL probably has the O and D demand to make this work. Smaller hubs such as CLT and PIT depend on the connecting traffic to make them profitable. Turn times at the outstations are probably timed to get them back to the hub during the appropriate bank. It is not perfect, but that is the way the system works. Southwest does not bank their traffic, but then they do not serve the small and mid sized communities we do. Thus, when you fly something like LAX-OAK, you have enough traffic where you can run flights constantly all day long.
Our ground time has traditionally been long, even with Metrojet. Although the product was set up for short turns, we found we could not perfect the quick turn, considering labor restraints on cleaning, etc. Not to mention, our passengers and flight attendants didn't quite get in sync with the cabin pick up routine prior to landing. Metrojet turns were routinely 30-35 minutes and that was a push. Trying to reeducate the passengers didn't help unless contracts were modified to reflect those changes. Never worked.