If hunting one animal only on a trip, I generally take a full box with me in truck or base camp, and carry ten or twelve with me in the bush. More if hunting two or more critters. That always seemed excessive, since most animals are taken with one clean shot. But I once actually used 14 shots when trailing a wounded deer in wilderness area for several hours. The deer had a broken front leg and another wound in the shoulder that slowed it down so I could just barely keep up on the trail. I had two either ### tags, and the wounded buck was elusive, giving me only enough time to positively identify it as a deer while it dove again into extremely thick cover. A raven finally caught on to the commotion and led me to that deer and I snuck up and finished it in its bed. I certainly wasn't proud of my shooting that day but I was glad to finish what I'd started about six hours earlier. A situation I never plan to repeat, but I still prefer to carry enough ammo "just in case" such a situation might ever happen again.
Another time I was on a moose hunt when five timber wolves ran across the ice of a beaver pond like a shooting gallery in front of me. Five shot later, I went on to hunt moose and still had enough ammo to feel confident that I had enough.
Realistically, most hunts require one or maybe two shots. The extra cartridges are more often never used or are used to check zero after a fall or some such.