OK, I'm FAR from an expert but here are my thoughts. Anything over 9 inches to me is a Chopper. Choppers are fun and impressive and some of them chop WAY beyond what their size would indicate. BUT for an "EVERYTHING" knife, they just don't have it. Oh you can do a lot of smaller knife tasks with them, but by being so large they are clumsy in my opinion for some of the "FINER" work/jobs that would be required of a "There can be only one" blade. I base this mostly on my Youth Running around in the Hills of Missouri, and later the Rocky Mountains of Idaho. I carried a 10 inch Bowie knife (the Infamous Negrito Bolo) and it did suffice for everything I asked of it (I carried a 6 inch "Hunting Knife" in my youth, the Bolo was After I got back from my tour in the Philippines.

I did everything from cutting down trees and "Skinning them" to cleaning rabbits and killing/butchering a Goat with the Bolo. BUT the tasks were made more difficult by the larger blade.

I Personally think the "Perfect" survival blade will be one between 4.5 and 7.5 inches, depending on the blade profile and thickness.

IF ever caught out I would do my very best to make sure I had at least two knives, a smaller 3-4 inch detail blade and one on the larger side for other tasks.