For the most part I use the same batting in most quilts. Then, When I piece them the "new" batt is the same and quilts the same. Do be careful about mixing batting types because different batts quilt differently. I also use my leftovers in a variety of small projects. But, I never let it go to waste as it is too expensive. Another thing I am working on that uses batting scraps is to make a stitch and motif album for use when I need to choose batting, threads or quilting motifs. I am having fun doing that.