Glad to hear it worked well for you, Tara.
I find that by having more even heat distribution at the center of the cake, it bakes up pretty flat, too. I use one, or more, in every cake I bake--6" and larger. For a sheet cake, I use 5 in an "X".
If you want to "upgrade" from the flower nails--they can rust, oxidize, or discolor over multiples uses, I strongly suggest these heating "cores" from Ateco. They're stainless steel, completely flat, and I think they're worth every penny.
If you google them, you can find them at various places online and they carry them at Sur La Table.