Mag pouches, I have 5 on my belt.
Mags themselves, I have at least 10 (18 for my main gun) for each gun I use in competition...it’s always a good idea to have plenty of extras for reasons stated above, plus, if you preload them all and keep them in your range bag, it means less loading between stages. Just don’t mix up the used ones with the fresh ones or you will end up having a lousy stage...lol...ask me how I know.