The severity of the problem seems to be related to the number of lathe cross-sections. Does anyone remember the solution, or is it a bug?
I don’t think it’s a bug – I think it’s a limitation. For patches to be legal, they rely on the patches next to them. When you flatten a model, the patches split along a seam so that one side has legal patches and the other doesn’t. Even in the book, the example cylinder they show has 8 patches. When flattened, it’s only 7.