We'd say it depends entirely upon the RP. Some RPs suffer if they go too slow in the intCk-->OoC-->IC, others suffer if its done too quickly. the more complex an RP, the longer it usually needs to take. Our own GMing project went through almost a year of planning between versions, but then we did go a bit further for the planning than most do. Some players can throw up an extensive sheet in a matter of days, others need a week or two for such.

We tend to hold to that more time is usually better than rushing. We're slow to approve sheets, but we want the sheets to be fully functional before we do, so that we do not have to deal with poorly made characters later on in the RP.