1911: at least a dozen, but of course they're interchangeable between the three different 1911's I have now. Buy another couple of Wilson 47D's whenever they're a good sale price at gun shows.
FN FAL: 6 or 7 20-rounders but I buy more every time I find some reasonably priced at gun shows.
AMT Backup: 2
All the rest of my guns just have whatever they came with.
I've got 11. Some are rebuilt with Tripp kits, some just Wolff XP springs. Some 7 round (started that way or are now after the Tripp kits) and some are 8 round using the replacement XP Wolff's.
I try to keep 2 of the 8 rounders that I feel the most reliable ready and loaded for carry.
Never less than six for a carry gun or any gun you think you might carry one day. However I agree that all things considered there can never be to many mags.
I have ten sten mags for my Macs,Twenty for my ARs,and eighteen for my 1911s.Plus others that are sitting in my safe.I also keep 1000 rounds of .223 and 9mm stored in my safe.Got to be ready for those zombies.