I could be wrong, but I believe it updates about every hour. If you want more of an exact number per user at any time of the day, each stat on a user's profile updates automatically with every post, review, submission, level change, etc.
I do know that the TVRage Calendar
updates every 15 minutes, so if new episodes are added or if you choose to exclude shows, the calendar will refresh every 15 minutes. Just FYI.