If u have a disc that will not work at all it's worth a shot I guess (can't break it anymore) but like said above the idea is to remove a very fine layer of the disc (scratches the reader skips/sticks on whatever).
Very easy to overdo it and take to much off of one part and not enough of another I would think.
I had a device that spun discs with a little sanding pad in it that saved a few of my sega dream cast games that died way back in the day.