The most ammo I've actually had to fire while hunting, was 17 rounds of .303. And off to my left, my hunting buddy emptied his rifle and was reloading when the shooting stopped LOL
Not often a dozen or more BC timber wolves present themselves at 75 yards and decide charging you is a good idea. Regardless, it happened to me

So now I always (and did before) carry approx 30 to 40 rounds of the ammuntion I sighted the rifle in with. Loaded rifle, spare mag or ammo holder on buttstock, 10 rounds in a ammo pouch on my belt and the remainder, wrapped up in my day pack.
Better to have it and not need it VS being in a situation where need it and used it all up. Kinda like toilet paper hahaha