I have done several tires that have RideOn installed. What I found was that it only ran in about an inch wide strip in the center of the tire. That, combined with it failing to prevent some flats that it should have, led me to quit using it. I realize that RideOn is not unlike balance beads, oil, etc when it comes to proponents and naysayers.
Interesting....I've been using it for several years, and many sets of tires, and only had one failure to seal, and that was with a piece of sheet metal that sliced about a four inch cut in the tire!
Every time I was about to change tires, I would invite folks over to watch my torture test of the tire/ride-on, which meant I would drill 1/8 inch holes, stab it with an ice pick, screw sheet metal screws into the tire, run over boards with nails it it, etc.
Each time, the product sealed the puncture wound and held air.
It does balance very well, so well, that I've stopped using weights years ago.
While your correct, it will only cover the center strip of the tire(s), the instructions state this, you can't really expect it to seal any punctures near the edge of the tire, or near the sidewall.
The problem most folks complain about, is them using the product incorrectly, meaning, they pull the nail/object out, then sit there and watch the air hiss out, and the tire go flat.
If you read the instructions, they state something to the affect of removing the object, then carefully RIDING the bike so the Ride-On is forced into the hole. If you don't ride it after pulling the nail out, to force the stuff in the hole, it won't work.
This is not a problem with the product, but the user.
I've removed large nails, screws, and even an Allen wrench from my rear tire(s) while traveling, and always made it home.
Remember, this product is just designed to get you out of harms way, and to safety, it is not meant to keep using the tire after its been damaged.