I took a class a few weeks ago that included paper piecing. Instead of placing the material on the back to the line. She folded it along the line. Then sewed along the folded line. It kept the bulk of fabric trimmed as you worked. Keeping the seam allowance trimmed before every seam. It makes it easier to place the fabric in the correct place. To me the other way is working backwards. Not my favorite way. I hope this makes sense.