If you're on the waiting list and offered a ST you can only defer once. It's not like there are unsold season tickets, they just keep going down the list until someone takes it. (People often defer as they want a particular stand to be near family or friends.)
These threads are getting a bit "fixtures" now it seems. I know of several batches of season tickets that are shared between several families. While the demand for tickets is high I don't see the club doing anything about it sadly.