it all depends on how much time and effort you put into it. i know i posted this somewhere else but..

joe satriani practiced 15 (fifteen) hours a day with a metronome as fast as he could when he was learning guitar. he practiced all his scales, modes, everything and memorised the whole fretboard (which i highly recommend) and thats why hes so good. playing good guitar is not an overnight success.

EDIT: he still practices 15 hours a day