Wow, I don't believe they're advertising a junk repair with 5200.
I repaired a 48 inch tear (approx 1.5 meters) on my Avon that crossed over two seams with an internal patch and an external patch.
The internal patch took about 1.5 hr to prepare and complete. The main holdup was cleaning out the tube internally due to moisture and dirt, and removing the duct-tape residue that I put on in an attempt to keep rainwater out. The internal patch was approximately 98% air holding. There was a few tiny fizzy leaks / weepage, but they were small enough where a little cured adhesive alone would hold them in. The external patch sealed them up just fine.
Gooping stuff up with 5200 is never the correct solution.
Pardon the UV degradation, I've slowly been adding material to the topside to compensate.