Rifle dry fire is just as important, although rifle accuracy skill falls off much slower than pistol.
For 3 gun stuff (AR), I generally practice with the bolt locked back for trigger/safety work, and bolt closed for mag changes. All loaded mags are at capacity minus 1, with a spent case as the top round. This gives you a workable safety and trigger for target transitions, mounting the gun, and grabbing/dumping guns. The closed bolt mag drills are to prevent failing to fully seat the mag, and allow for safe handling of weighted magazines. I've screwed up a couple of bolt lock reloads in recent matches, which is incredibly infuriating after the fact.