The 80/20 Principle says that 80% of the the results come from 20% of the effort. It's seen throughout life - from roads to sports to customers to music. There's a myth that it takes hours and hours and hours to learn jazz. Part of that is true - it does take hours and hours to master the music. BUT you can start sounding like an authentic jazz guitarist quickly by focusing on the 20% of things that make the most difference. That's where 80/20 Jazz...