Thanks, GW. Three per person is sounding about right for the range. And you bring up the point of CCW, one in pistol, and two backups. That's good. I can always wish I could use 14-19 round magazines, but if 10 is what I'm restricted to, I'll have to obey the law.
I've read that you shouldn't force the maximum number of rounds in to a magazine. But load the allowed number, then chamber a round. This reduces the compression on the magazine spring, and prevents the spring from taking a set. And you're prepared for cocked and locked, or hammer down carry. Also, you want to cycle your magazines through your pistol so that each is used, and you aren't relying on the same one all the time.
If you haven't dropped your magazines in the dirt or mud, how often do you take them apart and clean them? If you make regular use of each magazine, and aren't having any problems, should you bother cleaning them internally at all? Just wipe them down, maybe rub a drop of oil rarely over the outside surface. (If you live in a damp climate, you may want to check for rust on the internals occasionally.)