Very interesting thread - banjo's tend to go out of tune easier than guitars because vellum is more susceptible to atmospheric changes than wood.

we had a lad come along for lessons on his new banjo - we spent an hour with him showing him how to tune up and an open G chord - then made an appointment for the following week for another lesson, He didn't turn up the next week but did the following week when he apologized for missing his lesson the previous week because he had been playing it at a gig!