And yup, gotta get out there to actually practice this stuff, first-hand.
Things like switchology, beam pattern, the interaction of the light with gunsmoke, decreasing output as the lens clouds-over with carbon from the muzzle-blast, etc. - it can all come into play: and the time to find out is *not* when you actually need to use the weapon in self-defense!
There's some things that just aren't going to be apparent unless you're also in that darkened atmosphere, but for things like how the gun handles when you've got the light on it (the shooter "pushing" the gun, when he was pushing on the momentary switch), realize that a lit range doesn't preclude the use of the light - nor does dry-fire practice.