Metal Style Guitar Scales (3 Notes Per String)
There are two basic ways to play guitar scales. The first method uses a pattern that combines two notes per string and three notes per string, consistently has one finger per fret on each string, and causes the guitarist's fingers to periodically move down the neck (backward) when reaching for the next note.
The second style (featured in the metal style guitar scale graphic) always uses three notes per string and always moves the fingers up the fretboard in a diagonal pattern. This style is common in metal and shred guitar music as it lends itself to faster fingering. But this style also requires the fingers to stretch and reach a bit further because the fingers often skip a fret as four fingers are distributed across a span of five frets.
This style was harder for me to learn at first do to the stretch, but once mastered was much faster and easier. I found that the fluid diagonal movement up the fret board and the consistent 3 note per string pattern easier to play and memorize.