Brings us to someone like Les Stroud. Before Survivorman, he spent a year living in the woods in a tipi with his wife. Not everyone gets a chance to do that(I asked, but she wouldn't go). Nor is it possible to shuck the bindings of civilization and live in the wild like Nessmuk. Anyway, I believe you learn by doing. Any training a person gets never becomes a skill unless it is used. I think training gets your foot in the door, but time in the woods under primitive conditions is the true measure of an expert. I just don't know how you could validate a claim.