Just completed a recent custom order for some house numbers. It's a long one - so it was a long wait to get it dry and keep it flat. When sewing with fabric - measure once cut twice. Same goes for one off special orders like this. Make two, in case one doesn't make it. It paid off this time. One of the 2 cracked in the glaze firing. Someone said I was "lucky" I had another. I said, no not "lucky" just hedged the odds with a good plan. I always tell my students that when you making hand built slab pieces, it's always good to roll out extra, plan for some warpage, see how many days you have till it's the right leathery state. Make sure you cover your bases.