There is never a time whether I'm predator hunting, bird hunting, or big game hunting I have less than 3 guns with me.
I ALWAYS have one of my predator/varmint guns with me. I also ALWAYS have an actual backup in the truck or if waterfowl hunting, I ALWAYS have a spare gun in the case in the boat or laying next to my blind.
The 1 time I didn't have an extra gun with me I was actually guiding and the client had a circumferential separation while trying to make a follow up shot on a deer he hit. There was no way to get the neck and shoulder part of the cartridge out of the chamber. We ran back to the truck to grab a back up rifle (I ALWAYS kept one of my guns in my guide vehicle just in case). Well I had cleaned out the truck that morning and decided not to bring it. Luckily another guide was with clients on another part of the ranch and had a rifle and 2 rounds in his truck. We beat feet across the ranch grabbed the rifle finished off the buck before he disappeared. Otherwise it would have been a 25mile round trip or if a guy was just on a DIY trip....what would you have done?