King's take on it was he could see the scales he was trying to use, and how he would go off-key from a technical point, even though we, as listeners, don't hear the difference.

Music is mathematics given the blush of reality, and even music suggests that there are certain patterns in Nature that re-occur over and over, like the 12 modes. This pattern is an archetype that we see again and again. The reason Megadeth sounds the way it does is because Dave Mustaine studied a lot of classical music, and learned scales used by Bach and Beethoven (mainly the harmonic minor and melodic minor scales). Yngwie Malmsteen did the same thing. We recognize those scales without really knowing why, but that is why--those songs, like Für Elise, use a scale whose notes fall in the same range as other, more modern songs, so we hear similarity.

I would just focus on learning scales, and learning chords. If you want to get fast, learn scales, and then only do triplets three notes within the scale that you practice fast with hammer-ons. Yngwie Malmsteen would be a good start for you to do that--his triplets are ridiculous.