For a long time I thought banded horns were a regional NC thing from the Piedmont. Little did I know they came from all over. Jay's Volume I banded horn book is really fascinating. Can't wait for banded horns number 2 that will have NC horns among others.
I agree with Tim's comment. Sacrificial wear area. On the other hand, some of the banded horns are so elaborate that the bands have to be (at least partly) decoration.
One thing that sticks in my mind is that the bands carved from the horn seem to be wider and lower profile than applied bands. Of course, now someone will post a picture of a carved horn with high, narrow, sharp bands! :-)
God Bless, Marc