I am constantly amazed at the experience & knowledge level on this board. This is such good information for every quilter. I have only been quilting a few years and was instructed to read the batting packages for how close to quilt so have never had this happen to one of my quilts. I always wondered how tying would hold up on a quilt that was washed often.
I have had this bunching & knotting up happen in some store bought, cheap quilts. Now I understand the why.