If an airplane flies 10 hours per day, when is it going to fly that extra hour? How do you fit that extra hour into that airplane's schedule for the day?

Say the airplane arrives in Rochester, NY at 11:00pm. You could fly it somewhere else that night but how many passengers are going to want to book a flight at midnight out of Rochester? Not very many.

An airplane arrives at the hub and sits for an hour and a half before it's next flight. It could depart after sitting only 50 or 60 minutes but that doesn't leave time for the inbound connecting passengers to make it to the flight. You could increase the utilization by shortening all of the turns throughout the day but that doesn't do any good if you make the connection time too short for many inbound passengers to connect.

The airplane arrives at an out station at 10:00a and sits for two hours before returning to the hub. It could depart sooner but that would have it arrive back at the hub in between banks and would add an hour, or more, to the passenger's connections. Many of them will book a different, more efficient connection. The airplane would then be at the hub too early to quick turn back out again because it has to wait for the other inbound flights to bring its passengers.