What about cadence, timing multiple shots? Does that matter?
Yes, but it isn't something that someone should be worried about right off the bat. The first training priority should be accuracy, second should be speed. When you get accurate enough fast enough to worry about cadence and timing multiple shots you will be well ahead of the pack.
Every once in a while it is also useful to step outside your game and try a discipline that focuses on where you are weak. Such as air pistol shooting to work on your accuracy. After working air pistol for a week see if your USPSA targets don't seem monstrously huge by comparison. In comparison I used to think 300 yards was a long ways to shoot with an M16, until I shot at 600 yards and 300 became exactly what it always should have been for me, point blank shooting.