I SITD my last quilt and when I started quilting the center afterwards I noticed all this fullness. Was so afraid I'd have folds on the backing or even the front but as I continued to stitch the fullness disappeared. Amazing. Think it depends on how intensive the pattern is too on how much of the fullness will disappear. Luckily mine disappeared for me. On another quilt years ago and I made this quilt myself so don't know how it happened but it did, the border at the bottom was way too full, no matter of steaming took enough of the fullness out for me so I went to Plan B as I call it. The pattern I was using helped too. I pleated the fullness in 2 places right where the stitching would come down using a piano key pattern. Got lucky there too and no one was the wiser. Should have taken a photo of what I did for future problems but didn't. I do keep an extra steam iron near my quilt machine just for those areas that become problems for me.