I have a similar method. It's certainly not perfect, but 99% of the time I'll be within two semitones, 80% within 1 semitone, and 50% of the time I'll be exactl

I have a similar method. It's certainly not perfect, but 99% of the time I'll be within two semitones, 80% within 1 semitone, and 50% of the time I'll be exactly right (percentages are approximate). Smoke On The Water gives me a G, Call Me The Breeze gives me an A, and so on. These are songs I've heard so many times they are just burned into my head.