Traditional animation techniques and 30fps software animation?
Yes, repeating every other frame works the same way at 30fps as it does at 24fps.

Animating on twos is done not because it looks better, but because it means less drawing and you can 'get away' with it. Nothing stops you from drawing every frame if you want the smoothest possible motion, and nothing prevents you from repeating a frame indefinitely when there is no motion.

If you really want to work at 24fps, you could always animate 'as though' you were working at 24fps -- your work will look sped up when viewed at 30fps -- and applying a cine expansion (3:2 pulldown) as a final step.