Though the internals of the 300B tube are larger than those of a lot of other tubes; the same components(cathodes/anodes/grids) & dynamics are present in all: (http://www.stereophile.com/content/search-perfect-300b-tube-page-3) (http://www.stereophile.com/content/search-perfect-300b-tube-tale-burn) Read the follow-up of the article as well, for further notes on burn-in(especially paragraph three).
