>I have a client that has a billing report that is about 10,000 pages long. There is one page for every record, actually. Anyway, I'm curious as to how I should divide this up. Should I let them spool 10,000 pages to the print queue? I really don't want to do this.

We did that, and it didn't work due to a misconfiguration. We had two print servers connecting to the same printer via TCP/IP. When a job on server A timed out while waiting for paper, server B would grab the printer connection. Then when the paper bin was refilled, server A restarted the job form the beginning. Utterly hopeless for cheque printing !!
We still haven't learned ;) Just changed network admins so many times that no one knows why it occasionally goes belly-up. Of course I'm just a developer, so what do I know :O

I'd recommend some way to log what is printed (so you can reprint what's in each group) and spool it in groups of less than a paper-tray full.

Also remember that VFP has as limit on the maximum number of pages in a report run.
Using small groups will definitely be a good idea all round.