i run the full 30. i've found that I don't need to smack the floorplate of the mag if I just ram the shit out of it in the first place. that's just the mags that I currently have, I can't speak for other people's mags and/or rifles.
that being said, I'm with you Reaver. I'm the same way, I always max out everything. whether it's "necessary" or not. I keep everything I have loaded and locked in my cabinet, bolt actions, shotguns, .22lr... everything, lol. I just don't like the idea of rushing over to the gun cabinet and having to ask myself "oh shit, which shotgun is loaded??!!" shit on that, just load every damn thing I own to max capacity and it doesn't matter wtf I grab.