I usually carry 2 blades, 1 small, 1 large. It's a funny thing, but when you actually live in the "bush", your carry preferences usually shrink. I have carried a Busse Battle Mistress (POS), a Cold Steel Bowie with stag handle (that could really cut!) a something from Chris Reeve, a Randall, Puma White Hunter, a machette, and, of course, a K-Bar. I also still have a Firestone Belt Axe (really like it for hatchet work around camp).
All did a lot of work--making shelters. In fact, once you establish camp, or merely just want to camp, a big knife is an anchor. It stays around camp to make fires.
If I were to go hiking, big knife would stay at home. If I were to go camping, big knife stays in camp, usually. If I were in the Military, that would be another story.
For general "bush" work, though the big knife is a shelter and fire maker. If you can make fires with enough available wood, or with a stove, then there is no need for it, IMHO. Shelter, if you don;t carry it with you, is the big chore that only a big knife, or hatchet would accomplish.
Your small knife (sub-5") accomplishes most tasks. I have carried a Russell Belt Knife for years and it had performed so many small chores I can't remember them all. The Russell Belt knife is very useful indeed. Along with that I carry a SAK because it has some useful tools for small simple chores.