At what point in his life does a boy become a man?
All these differences exist in a continuum. For some players (myself included), 1 11/16" is *just* too small, while 1 3/4" is *just* enough. Of course, I am generalizing as well, since many other factors come into play: the spacing at the saddle (which also affects spacing across the fingerboard), neck profile, how far the outer strings are from the edges, etc.