Hmmm - The largest quilt I've done on my machine was about 65 x 85 inches.
I stitched all my lines the same direction. My reasoning - if the fabric was going to shift - it would all go the same direction instead of zig-zagging. My machine: An older Pfaff 1471. c
I only do stitch in the ditch and straight-line quilting.
Sometimes there is a bit of a "poof" when I go crosswise to the first lines of stitching, but I usually don't get pleats.