If I change out my bobbin before it's completely empty, I put it aside to use when I'm basting my quilt sandwich on my frame. It doesn't matter then if it runs out while I'm basting the edges. On my regular sewing machine I'll use it when piecing my blocks or as I'm doing right now, I'm working on a bunch of wedding ring quilt blocks (embroidery design). There's a lot of applique steps to this design so using up all the leftover bobbins as it's never going to show on the backside as I'll be adding batting and backing later. I also hate wasting thread. If it's my quilting thread, I also will use it when I'm hand stitching the binding onto the backside, again not wasting it.............that is if it's in the correct color I need.