At least with what DVDs I have of yours I don't recall seeing or hearing anything about learning scales on the banjo. Could you maybe post about scales on your Daily Blog? Thanks!!
This student is correct in that we don't teach scales on any of our DVDs, with the exception of the Blackberry Blossom (aka Medodic) Video. We don't teach them because we don't consider them particularly relevant to Scruggs-style playing (again, with the abovementioned exception). Because the banjo uses rolls, it gets the melody in a different way than the other instruments (guitar, mandolin, fiddle) that play liner melodies. We do still use the notes that are in the scale, but it is more useful to think in terms of licks, which work nicely as independent pieces that you can then move around and use in different songs.
Learning and practicing scales will not help you develop the skills you need to play with other people in a jam session or to improvise with licks, and those are our goals for all our students. So, unless you are the kind of person who really likes scales (some people do, I can't imagine why), don't worry about them.
Now, if your aim is to play the banjo in a more progressive (think Noam Pikelny), or melodic (Bill Keith), or jazz (Bela Fleck) style, then you definitely should learn all of your scales--all twelve keys, major and minor. But I don't feel that many of our Murphy Method students fall into that category!