Re: That's not MY ship...!
3-5 is a pretty reasonable loadout for a Federation ship. Any more than that and you're gonna start taking up more space than is necessary. (Tube length and clearance, loading mechanisms and storage magazines. I doubt there's one central magazine - there has to be a decent supply near each tube, I'd imagine.)
I promise you I will listen to what has been said here, even though I wasn't here.