I made lots of pillows in the drapery factory while I was working. Our pillow covers were the same size as the pillow molds. Plus seam allowance or the pillow turned in the casings. To get them into the casings after they were sewn, we would wrap them in plastic wrap and shove it in and pull out the plastic sleeve. Worked every time and made
nice plump pillows. We sewed them shut and move to the next one. Nothing went to waste.