Here's my take. Posting 1 book now and saying will post the rest 8 hours from now is an announcement. There is an announcement thread for that. If someone has only 1 book to sell, that is fine. If someone posts a handful of books and says will post the rest later, that is fine as well. We can tell when someone is using a FS thread as an announcement. It's not fair to the others that have legitimate FS threads, and they keep getting knocked down by people posting in an "announcement thread" As Arch says in the guidelines thread,
"Please do not try to be "clever" to find a way to post a single book so you can make an "announcement"