It depends on the use of the project. For a simple table runner, I might use only one or two layers of flannel. For mug rugs I often use something heavier, usually a cotton batting, that will better protect table from hot beverages. I often grab a mug rug for use as a pot holder, so I want it to be thick and heavy enough to protect my fingers. For wall hangings, it depends upon the effect I want to achieve .... from flat to puffy. I buy much of my batting for small projects at thrift stores, garage sales, or people cleaning out sewing supplies.