I'm doing a string quilt as you go right now. I have two rows done but I am not putting the sashing in-between the blocks and rows. I wanted the squares to line up with each other. I sew the front frabric together and then just fold over the backing fabric and machine stitch it down. I saw it on a video and decided that was what I wanted to do. I guess everyone does things differently. Maybe, if I ever do another quilt as you go, I will put the sashing in. For this quilt I think it looks better without.