I have made several flannel rag quilts and I always use Thermore as it is the lightest poly batting. I also either stitch an "X" across the middle using a "wave" stitch on my machine. I strongly believe in stitching each square to some degree and also using the light batting. Also, when I finally stitch the very outside edge of the entire quilt, I do two rows of stitching for durability. My granddaughter's 4 year old quilt has been washed every week for 3 years now (daycare & pre-school) and it is still in perfect condition. Only the best flannels - I do NOT recommend JoAnn flannels - very poor results when laundered. I made a quilt for another person who had already bought her flannel from JA and it was a disaster when washed.