I, too was taught to SID on seam line, but after trying too many times to acheive I had that AHA! moment.
If I can use seam Line? to stitch, why not go beside it. Not only did it become easier to quilt, but I am NOT just stitching over thread....
Does that make snse? I have changed many a students thought process but explaining this. I teach now to zig-zag (for those without fancy machines) or use a stippling, serpentine or feather stitch over the whole seam of piecing.
This then holds both sides of the seam to the batting and backing. Don't know how the ID part of SID came to be, but I actually think it looks better if you can see the quilting. IMHO.