I am a hand quilter and am now quilting a 90 x 90 quilt with cross hatching in a hoop. I didn't mark before sandwiching because I planned to use masking/painters tape. After much frustration and many tears I've discovered that it just doesn't work on large areas. I have removed almost as much stitching as I have put in because of uneven lines. I tried marking but with the batting (poly) I can't get accurate lines. So, I have vowed to mark all my tops prior to sandwiching no matter what the design is. It will certainly be faster than ripping out my stitches.