I have conflicting info on the proper use. Are they meant to cut a cake baked on a sheet pan or intended to be placed on the parchment lined pan & then filled with batter for baking?

This ring is used for both. I have made a chocolate mousse cake that needed to be unmolded and I have also cut out cake to make a tiered cake. It’s very sturdy and not a flimsy piece. Im happy with it and it has multiple uses. You don’t need to use it just one way.