First, I have comment "I practice reloading my magazines fast"
You do? I just use a mag loader, 1 round at a time, no hurry, no sense getting sore thumbs
I used to go to the range with about a dozen magazines there were pre-loaded. One day I read a story written by a LEO that normally carried two spare mags and a back-up gun. The reader's digest version is the firefight lasted 59 seconds in which he expanded all the ammo he had except one round. I got to thinking that my EDC gun is in Condition One with 9 rounds. My two spare mags have a total of 16 rounds. One would think that is adequate however, the LEO that wrote his story said his magazines held 17 rounds each. I think that the probability of expending all my ammo is very slim but why not practice for something I hope will never happen. Hope for the best, prepare for the worst. I usually have a couple of boxes of ammo in a range bag all the time.
I have developed a lot of thumb strength and can load a magazine a helluva lot faster than the guys that use mag loaders. Yup, my thumb hurt in the beginning but it no longer gets sore.