At the extreme, fighter pilots fly almost exclusively training flights because we're not actively waging war at the moment.
There are a few military bases in the area - Belvior (Army), Quantico (USMC), Andrews (USAF), Pentagon, and some smaller ones (some of which have helipads, but no helicopters on station). And lots of shuttling of DoD and other government VIPs from location to location across the DC metro area.