“You need a sufficient amount ammunition to be able to continue training while the supply has dried up.”
I certainly agree with that part. If a person has more guns than he really needs, the scenario crops up where one forgets the idiosyncrasies of each weapon, and when needed may not hit the target.
In other words, they need to be occasionally fired to stay familiar with that particular weapon, and that occasional use uses up lots ammo.
Tonight I will be practicing with a favorite revolver, probably use up 30 rounds or so of various types.
When you have multiple handguns and long guns and don’t shoot all of them regularly that muscle memory disappears in a hurry. I have spent the last couple years devoting most of my recreational time to motorcycle riding. I decided to get everything back up to speed in the firearm department and found that I couldn’t remember half the crap I thought I did.