petthefabric, what Judy has us do for this quilt is the same as square in a square. And like most blocks, there are different ways to do it. Covered corners is very common and most people find it the easiest way.
I did the Gypsy wife quilt, and there are an assortment of square in a square blocks and the directions have you do covered corners. I gave up and figured out what the measurement would be starting withe the inner square, and then it worked fine for me. With this mystery, I cut off the corners of my background for sewing on the dark, but did the other side as covered corners because I cut all the squares ahead of time. And my blocks turned out larger than I wanted, but had I cut them down I'd have lost the points. So I eased them all in. Looks ok in the end.
But I did find a good use for most of the cut off corners for the light and medium fabrics.
here is my floppy. I started out cutting 4x to have a larger quilt, but then went with 5 rows x 6 rows with a 12" border all around and used 4 of my extra 6 stars in the corners. It's ending up 84 x 96.
