Mark
It really depend what you play and what you want achieve with the guitar.
Anyway learning all the notes doesn't have any side effect. Start playing the G major scale on the low E string and think the note you are playing (g a b and so on). After a while you will know all the notes on the low e than do another scale on the A string and so on. There are theoretical explanations of the freatboard but memory will work too.

Carmine