I'm not sure of your question, so I'll answer both ways.
I like to own at least five (5) magazines for each model of pistol I have. I have several 1911 45 Autos; I don't have five for each one, but I have something like fifteen that will serve in any of the pistols I have. I have seven magazines for my H&K USP40. I only have three for my Ruger 22 pistol, but it's a target gun only and I'm pretty careful with the magazines.
I have a 1903 Colt Pocket Pistol in 32 ACP. Only one magazine for it, but I don't shoot it much.
For carrying, I always have two reloads for an open belt gun, and one reload for a concealed gun. To paraphrase John Wayne in "The Shootist", "If your gut tells you to carry more, carry more." The reloads applies to magazines, speedloaders or speed strips, depending.
I don't plan on being attacked by the Red Chinese Army where I live. Ten rounds should get me out of any problem I might encounter, as long as I can deliver them on target, on schedule.