Magazines are the heart of a semiauto pistol ... unless it uses an internal magazine and/or stripper clips.
Because of that, I like to make sure I have at least 5 or 6
functional magazines for each of my defensive pistols. I've been known to have many, many more.
What I think is interesting is how the major manufacturers have mostly started to supply 2 magazines for "civilian" pistols and 3 magazines for "L/E" pistols. Perhaps they're noticing a trend among their customer base ... finally. Remember when only 1 magazine came with a pistol, and spare magazines were often something that your local gunstore had to order for you?
When I recently bought my G26 it came with 2 magazines (promotional sale, not an L/E order), and I bought a third ... and a week later I bought 2 more. That way I can have at least 1 magazine dedicated for the Range, if not 2 ... and 3 for carry use. There are times I only carry a single spare, however.
When I own at least 6 magazines I usually keep 2 dedicated for Range use ... after ALL of them have been function tested for the first several hundred rounds.
I can't speak to the subject of diminutive pocket guns in .22, .25, .32 & .380, because I haven't carried 3 of those calibers in years (never owned a .32), and when I did I only had 1 spare. That was because I didn't shoot them nearly as much as I did the "larger" defensive pistols, and generally carried a larger caliber weapon, anway.
I often see folks attend a CCW class with only a single magazine (it's been previously decided that we won't "require" folks bring at least 2 magazines). If for no other reason, I think at least 1 spare magazine should be owned & carried for the purpose of resolving magazine related functioning issues.
Magazines should be inspected frequently, properly cleaned & maintained (including magazine spring replacement as needed), and replaced if they become the least bit unreliable/unserviceable.
Personal risk assessment and equipment selection is something that only you can determine, and the more access you have to proper instruction & training, the more informed you'll probably be when you make your decision.