I haven't ever participated except to provide a cake myself. I doubt if you would buy more tickets than you would want to have cakes. The idea is to have the exact number of cakes as the number of blocks. I think this would be run according to the wishes of whomever was in charge, how big the event was, how many cakes were provided, how big the interest was. It could get like a bingo game - lots of tickets sold, not so many winners.
The church we used to belong to had raffles for homemade cakes. You could tell by the prices offered who the really good cooks were. The money went to foreign missions.