I do not adjust my thread for a bed quilt. However, I usually use Bottom Line in my bobbin, or sometimes So Fine. Both are thin polyester threads, but they are pretty strong. I think quilting density might also impact how much tension is put on your stitches. At my house, my couch quilts seem to get treated much more roughly than my bed quilts. I haven't yet had any bad experience with bobbin threads breaking in a quilt, but I imagine time will tell.