I think it's best to stock and maintain as few calibers as possible. Me, my wife, my kids, and my parents all run 9mm, 5.56mm, and 12 gauge. Just those three. We got rid of all our guns that shoot other calibers (30-30, 308, 2.47, 7.62, 40, 45, 20ga., etc.)
It's less magazines to worry about. It's easier to stock. It's easier to train.
I'm not a "gun person". I don't hunt or go shooting for fun. I just want the minimum tools necessary to provide security for me and mine without a lot of expense, tending, and bother.