Curious as to why assigned gates and departure times at DCA frequently change before departure, before the day of departure?

I was connecting at DCA, with both flights on regional jets. The gates for both flights changed (changing 3 times in one day for my outbound flight), and the time for the outbound flight even changed twice, becoming 10 minutes early and then moving back to its original time. All this happened the day before departure.

FWIW, I walked between the B/C and C piers, and the time from one Admirals Club to the other, even going through security, was 5 minutes. Much better than the shuttle bus.