I always make a sample block to make sure that I will like the final result. I have often changed my colour placements as a result. It is also to check that the instructions are correct. I also make an extra block from every quilt I make. Someday, I will sew them all together into a sampler which will be a wonderful record of all of the quilts I have made! It is also a great way to decide which way to press my seam allowances.