As I understand it, the system will "hold the place" of each deleted post from threads. So once a post is deleted by a moderator, nobody can see this post any longer, but it still occupies its place in the thread.

For big threads (like the DAL L&G or the Spirit of NKS), there have been many posts deleted. These deleted ones could add up to 10 pages or more. When you go to a thread like that, you are taken to the last page and last post that was not deleted, even though it says there are more pages.

Hope this clarifies things.