Notwithstanding some folk's need/desire to have as many mags as possible at the range, in just about all other instances, the real question is "how many mags can you carry and still accomplish your mission?"
Realistically, I only have two missions with firearms.
1. Self Defense and then 2 mags is plenty, but for my second mission....
2. Range time. And then, no number of mags is enough.
And something that people sometimes forget...
Even though you have a boat load of mags, you still have to be careful at the range.
Shooting 300 rounds in an hour just because you have them loaded in the mags can still hurt your hands.
Dave