I had a customer complain about the seams on the corners of a fondant ribbon. The ribbon trimmed the bottom of each tier of a three tier square wedding cake. I trimmed the corners to make them flush, then let them go at that. It was a traditional cake, with only frilligee as additional decoration. I have high standards, but I thought it looked good. The bottom tier was a 14 inch square cake. Too big for one fondant strip, I think.