I'm glad that explanation was helpful! I see Penski uses a similar technique.
While I'm on a roll, thought I'd mention that batting has grainlines just like fabric. One grainline (crosswise) is stretchier than the other (lengthwise). It's best to layer your batting so that its lengthwise grain is running with the length of your quilt. It makes the quilt sandwich more stable. I think that tidbit of information was in both Harriet Hargrave's book and the book by the author whose name I can't remember (except that I remember that she worked in her parents' Bernina dealership, is colorblind, and won AQS a couple of years in a row for her machine quilted quilts).