When I do the straight stitching on sashing before FMQ, I start in the middle of the quilt and stitch out to the edge of the quilt in all directions. I used Hobbs 80/20 fusible batt but the fabrics still move a little but if you get the "extra" to the edge it helps. After the whole quilt is stitched outward in the sashing, I quilt inside the stabilized squares. My Machinger gloves really help with smoothing the sandwich as I approach intersection. I think intersections are where most problem puckers tend to occur.