Charles Andrews and Noah Gellner have both posted on paint durability and paint quality. I watched my friend Les Lunas for a few years, and he taught my wife. What most folks don't seem to realize is the absolute necessity for getting the naked frame absolutely clean, w/o any fingerprints, dog hair, or even the hair from a gnat's eye. Les would then etch with the iron phosphate solution, never touching the frame, let it dry, examine it, and iterate until nothing more could be done. At that point, it was finally ready for Corylon (?), a tough two=part epoxy primer. And that would get examined, millimeter by millimeter, for any imperfections that required a bit of fill applied with a toothpick and sanded out. Then came the Imron.
If the surface preparation is righteous, you can get a durable finish. If not, it's hopeless because the layer cake of primer, paint, and clear has nothing to hold it in place.
It's sort of like setting up a machine tool. Sometimes it takes longer than the actual machining. And that's why a really good paint job done the traditional way is expensive, regardless of the paint brand.