I made a rag quilt using cotton on top and 2 layers of flannel. I didn't stitch an "x" in the blocks because all 3 layers is caught in the seam. I used my Accuquilt Go so I know the blocks are bigger than yours. I did prewash everything though. I bet I have washed it at least 20 times in the past 2 years as my cats seem to enjoy laying on it. I've not had any shifting at all. It is my understanding that the "x" is used when using actual batting in the quilt to keep it from shifting and bunching. You will be fine not sewing the "x" on your blocks.