I made an Irish Chain once, and discovered AFTER cutting all my strips, sewing them all together, slicing them up the other way and sewing the slices into blocks- that I didn't have a quarter inch seam! All of my block A's were a different size than my block B's!
And just yesterday I left a bag full of fabric I had been using on the floor next to the chair I had been sitting in, and the next morning the cat used it as a litter box! Arghhh!!!