I think it depends on the student…I never tried any of the “quick” methods, but I always wanted to. I took traditional piano lessons for about ten years (3 different teachers), but after the first five years or so, I never felt like I improved (I was never better than “average” — in my opinion). Anyway, I guess I don’t have an actual answer to your question, but I definitely felt like I needed a change, and that anything would have helped me to improve at that point, but my parents didn’t agree — they were only willing to pay for the “traditional methods”, and I couldn’t afford anything on my own!