It can vary for me, but I tend to spend more time on those from more "realistic" settings, although even fantasy characters can, IMHO, be helped with research. For isntance, I've done about a month worth of gang research for a character who was suposed to be an ex-gang member, a couple of weeks on jaguars for a character who was a were-jaguar, as well as a few days research on various polynesian cultures since the GM was letting me create a lot of the culture the were-jaguar came from and I wanted it to be a tropical island culture (I know jaguars don;t come form polynesia, but it was a fantasy setting, and the environment would suit them well).
Right now I am researching leopards to play a were-leopard.
I've also, of course, used my own life experience as a soldier, writer, web geek, musician, waiter, martial artist, and construction worker.
Does anyone else put this much time and effort into character creation, or is it just me? I tend to treat them as though I were writing stories about them, and in fact, do write quite a few short stories featuring my RP characters' "unofficial" adventures outside the gaming session. One of them I wrote about 300+ pages worth of short fiction for, most of which had nothing to do with events in actual game sessions.
Am I alone?
(x-posted in my LJ)