I saw this related question: Exchange 2010 offline address book does not update but the answer's blog post no longer exists.
If I create a new mailbox, and even if I manually update the OAB and then go into Outlook (in cached mode) and download OAB updates, it still doesn't show the new mailbox in Outlook 2010 until the next day.
Like the answer in the linked question, I know that the mailbox role needs to get a copy to the client access role, but both of these roles exist on the same server in this instance (there's also only one server at this Exchange org).
So, the real question is, how can I manually force updates to get the OAB on the server and the OAB on the client to show a new mailbox immediately (or within an hour) instead of saying to users "they'll show up in the GAL tomorrow"?
Best Answer
See: Exchange 2010 Offline Address Book replication/distribution schedule?
So we now know that running Outlook clients will check every 24 hours and that the default OAB compilation time is 5am... New Outlook instances seem to check a few minutes after startup. So the distribution is fairly random.
This is what worked for me when I had terribly-impatient users...
Outside of this, people can see the update address book in the web client or if they're using Outlook in online mode.