I think you might have missed my point.
If you practice, one or two rounds would be enough...leaving a bunch left over. If I was using it in combat, 17 rounds in my Glock makes sense. And I am not advocating limitscarry 30 rounds if you want.
Bill Jordan put it this way. “A 6 inch deep creek just might have some deep holes”. Probably would not need all that ammo but you just might.