It's generally accepted that Terry will sign a couple of items (sometimes they insist on one item) per person. Some people take the mickey and turn up with their whole set of books and expect them to be signed - and Terry usually obiges. But not only is that unfair on everyone else queuing, it's also unfair on Terry as he suffers from repetative strain injury to his wrist and I've seen him at signings with his wrist in a bowl of ice water.
Please be a bit thoughtful when you go to a signing.