Traditionally, Sashiko stitching was done through two or three layers of cloth. With modern pre-printed Sashiko samplers the decision whether to stitch through one or two layers is up to you. If you have repetitive use injuries or arthritis in your hands, you may find it easier to stitch through only one layer. If you are having trouble maintaining good stitch tension and your stitches are bunching, try adding a second layer to help hold your stitches in place better. Experiment and find what works best for you.