The first generation Park GP-1 patches were notoriously unreliable and gave the whole idea a bad name. The later GP-2 are supposed to be better but I never tried them after my first experience with the GP-1's.

I carry a spare tube (or two), change the tube on the road and repair the leaking tube at home. One problem with on-the-road repairs is finding the hole in the bad tube. The leak is often so small as to be undetectable unless you use floor pump to really inflate the tube firmly. Sometimes I even need a bucket of water to detect the bubbles. A frame or mini-pump won't do it.