The way I feel about it - - -
No firearm that requires a detachable magazine or a clip for proper function is complete without at least one of those items. In other words, it is silly to offer a Glock 19 and two magazines, say, unless there are two in addition to the one in the pistol. Typically, new Glocks are packaged with one spare mag. An M1 Garand is incomplete without at least one en bloc clip. An M1A, HK91, or FN FAL is not a functioning firearm unless it has a detachable box magazine.
An SMLE or 1903 Springfield, though, will work fine without stripper clips, though the military efficiency is badly compromised.
Few revolvers require clips to operate properly, and I know of none that require a speedloader. Which being said, I usually have my spare ammo in Bianchi Speed Strips when I carry a small revolver.
All that aside, I have no firm idea the total number of spare magazines, stripper clips, and speed loaders I own for my various firearms.
One extra for both my Savage Scout and Enfield No. 4 Mark 1, though both are easily loaded without removing the detachable magazine.
One extra for a few pocket pistols that I seldom carry.
M1 carbine mags, perhaps a dozen, 15 and 30-round.
AR15, about twelve, 20 and 30-round.
M1A, about six 20-round and one five round.
1911 series, maybe 20 in seven- and eight-round, plus one spare six-round for an OACP.
Browning High Power, ten full capacity in 9mm, and four in .40 S&W.
Glock 19, six full cap and two ten round.
Best,
Johnny