I am not sure if this qualifies but it is fresh in my mind as I am in the middle of the project. I made a quilt top with hexagons that I absolutely love. I had another quilt design that I planned to make. Both are intended for my bed. So I got the bright idea to make a two sided quilt. Well, the hexi quilt top was already done, so I decided to modify the borders on my second quilt design to better "match" the size of the hexi top. When I tried to sandwich the two tops, I quickly discovered why few people make double sided quilts. At least not with more complex blocks / quilt patterns. So after hours of trying to align and smooth out the sandwich I gave up. I have now finished quilting the hexi quilt, and will sandwich the second quilt top and start quilting it next. So instead of 1 double sided quilt, I will have two quilts. Won't try that again..... that is my "learning experience"!