I'm having a hard time deciding why I should memorize the fretboard. I mean, If I'm playing the key of A then I know that one of the boxes is 4th string 5th fret, the A is 4th string 7th fret and the other two notes are beside those on the 3rd string. If I know where the A pentatonic scale is I know where that box is. Then there is another box starting on the last two notes of the first and second strings of that scale. Now I have two boxes. Another is over on the 5th and 6th strings but they start two frets up from the pentatonic scale.
Am I missing something? If I know where each pentatonic scale is then I automatically have the boxes for it.
Of course, everything Griff and the other guys here have said is true. Memorizing the fingerboard lets you immediately jump to anywhere appropriate on the neck and start to play in the right key.
I'm new to soloing and asking the same questions as you. It seems as long as you know where
any root note is on the fingerboard, which you clearly do, you can start playing in the blues box associated with that location and then easily play either up or down
the blues box connection pattern from there. And that should sound pretty darned good.
When you consider the dots on the fingerboard generally make it easy to shift an octave from your original starting note and do it all over again, you can certainly play all over the place, just not necessarily
start your solo all over the place.
Is that giving up a lot? I don't know. Someone might be really hard pressed to know you weren't a master of the fingerboard if you leverage the known location of just seven root notes (14 counting the octave shift) and the blues box connection pattern.
Me? I think I'm gonna put some little colored dots and/or some little diagonal stripes on one of my fingerboards to help me follow the root notes (and, thus, the blues box locations) and get on with trying to play.
A thought... Before you start memorizing the fingerboard, if you think you're going to want to try an alternate tuning and stick with it, now might be the time. :