7/16" is not nuts at all, that as close as it gets to a 1/2" hollow, which is indeed the most common. However, what you said about the 1/2" vs. 3/8" hollows doesn't make sense, cause a 3/8" hollow should actually have MORE, not less bite than a 1/2" hollow. Remember that a smaller radius means a deeper hollow, thus more bite, while a larger radius means a shallower/flatter hollow, thus less bite, but better glide. A 3/8" hollow is generally about as sharp/steep/small as anyone uses, that's considered a lot of bite. Personally I like a 3/4", fairly flat, but some guys like hollows as flat as 1".