When I was just a pup, my father taught me that my hunting trips should be "gauge specific". If you are shooting 16s that day, shoot 16s. Ditto 12s, or 20s.
My father was thinking this simplified logistics (20+ year marines think about logistics a lot) and was a safer way to play the game, as it eliminated the dreaded 20 cartridge in a 12 barrel snafu. Simple.
Carrying a double trigger double gun has simplified it even further for me. You have, in effect, two guns. There is a good chance one of the barrels is going to work even if the other doesn't.
For mulitiple day trips, I select a gauge, and a double, and just go. I haven't had my car broke into, but, have seen where it has happened, and I try to avoid having guns left in the car when it is unoccupied. For a time there, meth labs were sprouting like mushrooms after a rain in Pine and Aitkin county, but, that seems to be a bit more under control these days. Somebody who breaks into the car isn't going to get much from me. Jumper cables.
My backups live in the safe. I suppose I'll use them if a double goes to the gunsmith.
Best,
Ted