I have problem playing octaves regarding my plucking hand. Let's say i'm playing C (3rd fret a string) and the octave on 5th fret of g string, i will play ConAstring with my index and 5onGstring with my middle finger, but when i want to play sth more complex like dark necessities by rhcp, i have play the root twice and the octave once, and while using the alternate picking technique, i cant always play it with my index on root and middle on octave, and i seen pros cover of this song and they always use index on root and middle on octave. and to be able to do that you cant alternate, you have to go double index on the root and middle on the octave. is it wrong to use middle on root and index on octave? because i've seen lots other people avoiding that!