Over here "across the sea" I used batting between my flannel top and bottoms for my rag quilts. They did turn out rather weighty but also very snuggly and warm and they are the definate "go to" when my grandchildren want a snuggle and a story read or are just feeling poorly and want to hibernate on the couch. They adore them. I agree with the other posters, if you are using flannel in the middle I would cut it the same size as the outer squares and include it in the ragging and also use a contrast colour to add interest. My flannel tops and bottoms were screamingly different in colours and when they were ragged, washed and tumbled dried the resulting splashes of colours is very effective.