I've just made a small sample using this method and am very pleased with the result, all the more so as this is my first time making any sort of prairie points.
After a final pressing, I sewed 1/4 inches from the original seam to catch the new edges and thus keep my sample together. I think I also may trim away the initial seam allowance so as to reduce bulk.
Thank you so much for your tutorial! It's fun, easy and effective!