The last page in any thread should be 15 posts long. That is, once a thread reaches 16 posts the first post drops off and goes to page 1, page 1 only has one post. This way you don't need to flip back to the previous page to see the 15 most recent posts in a thread.
BTW I still think allowing compulsive thumbs uppers and thumbs downers full scope for their deviancy was a good idea, but alas I was shot down by many singular thumbs downs. Think of what a service to the internet this would be, while they're busy clicking away they're fingers are occupied doing something other than making posts.