Dave or David?

Is "Dave" really the nickname for "David?" I mean, how much is that really saving? I can see Bill instead of William or Sal instead of Salvatore…  But this is like people who abbreviate July "Jul." Not a lot of effort saved.
Maybe it's not a matter of saving effort, maybe it's trying to distinguish between names that are pretty common. Like in Mexico, the name Francisco is so common that many Franciscos are called Kiko, Kikin, Pancho, or Paco.
New friends sometimes ask me which I prefer, "Dave" or "David?" I never know what to say. Although I suppose that "Dave" seems more accessible, doesn't it? You never speak of King Dave, it's always King David. And that movie, "Dave" helped foster the impression that "Dave" is a normal-type name and "David" somewhat pretentious.
And then there's always Davey. That one really bugs me. Probably shows some latent insecurities. When I was little a family friend used to call me "Davey the kitty" but I don't know why and I never liked it.
I have no moral. I have no hidden Biblical gem to not apply. This is not a parable. I was just wondering.