On Food Network Cake Challenges, I often see them cut a hole in the center of several cakes and "thread" them down over a center PVC-type support. When that's done, how do you go about cutting the cakes? Do you leave them on the center support and just cut around it, or do you have to remove them for cutting?

It would be easier, I believe to remove the cake tier and cut it while it's on the table.