hello guys , what do you think are the absolutely most important stuff to know (memorize fretboard) for metal and melodic metal, progressive metal/rock ?

ill give a few examples

minor and major arpeggios (5 positions) also mi7 and maj7
minor and major pentatonics, hexatonics
major scale (7nps)
harmonic minor (7nps)
melodic minor ?(is this used/important) ?

what else do you recommend/know ?

In a lot of metal stuff they like to use the b5 (Blues scale) also add chromatic notes inbetween the scales. And in the minor scale try adding a major 3rd sounds pretty cool, also symmetrical scales and diminished.