For what it's worth, I also adapted this sort of mentality because in the last 6 years or so, Ive owned about 8 calibers in all respective categories of firearms. It was just too much ammo, too much variance in firearm action/consistency....and I felt I was only about 50% accurate with all my guns.
Now, I own/shoot .223, 9mm, and 45acp. I MIGHT consider a nice snub revolver purchase soon which would now add .357/.38
Now, I feel I am WAY more consistent shooting my guns and ammo purchasing/storing/inventory has become much easier. It all boils down to personal preference man. Just dont create TOO many rules for yourself that you will be unhappy with.