Was .36 ever used as an all around caliber?
Yes, in Scandinavia, I believe. Small caliber snaplocks were used to hunt both capercaillie (a type of big grouse) and elk (European Elk, Alces alces alces, what we would call a moose). Capercaillie were taken using headshots, while the elk were shot at very close range while being driven by dogs through prepared stands.
Maybe in Alaska by Russian/siberian fur hunters using similar snaplocks. Not much available on Russian guns, at least in this country.
As for the American frontier, which is what I suspect you were referring to, while I can't say that it was never done, I doubt it was done by choice. I can't recall any evidence for sub-.40 calibers prior to 1800 and the near eradication of big game in the east (and remember that buffalo, elk, and moose lived east of the Mississippi in the 18th century) and I think that the pioneers were a lot less concerned with economy of lead and powder than popular imagination would have it. (Not that it wasn't a factor, but it wasn't an overriding concern. I can't remember if it is Isaac Weld or Doddridge that remarks that some folks wanted a smaller bore (.40-something) for economy while others wanted a bigger bore for power).
It is my impression that earlier generations, including those of the early modern eras, do seem to have been happy with calibers and cartridges that modern generations would consider underpowered. This might be due to the fact that practices such as running deer with hounds and jacklighting game were accepted and normal methods of hunting prior to the development of the modern hunting ethos at the end of the 19th century, and the gradual adoption of bigger calibers is due to the desire for a sure kill under modern hunting conditions. Another, more cynical, explanation for the increasing power of hunting guns might be that gun and ammo companies need to be push their latest and greatest new products on an increasingly urban hunting population, and in practice that means increasingly more powerful and efficient ammo, whereas a small, low-powered weapons places a premium on individual skills which aren't easily commercialized nor all that common these days - we traditionalists aren't directly affected by what mainstream hunting population is doing, but we aren't necessarily immune to it either...
I'm kind of toying with the idea of trying to sell or trade off my extra .54 barrel in favor a .40 or .45. I kind of like the idea of an economical little bore suitable for both our itty-bitty local whitetail and small game...
