Do you have to pay at the same time you reserve a time? I could see this being abused if you don't need to pay right away.
"Hmmm....do I want to go to Chops on Monday or Tuesday? Oh well, I'll just register for both and figure it out later"
RCCL - Adventure OTS (Honeymoon!)
CCL - Carnival Miracle
RCCL - Enchantment OTS