Basic scales

But it does help.
  You see irish tenor banjo playing is all about playing tunes, and all tunes are based on scales. It'll be much easier for you to learn a tune if you already know the scale it's based on. It's your decision, but if I were you I'd definitely invest the time necessary to learn the most common irish banjo scales.

Here are the most common ones. Practice each of them slowly at first, and then gradually pick up speed as you feel more secure. Don't rush that process. It is much better from all points of view to play slowly and controlled than fast and sloppily.
  Each scale is presented twice, first as a simple one octave scale, then extended to the range you'd usually use on the irish tenor banjo.

D major

G major

A major

D mixolydian

G mixolydian

A mixolydian

D dorian

G dorian

A dorian

D minor

G minor

A minor