When a serving Head, I introduced whole-class (no choice) violin teaching to my 6 year olds. It was awful! But the ones who were still playing by choice 4 and a half years later in Year 6- wow! They were invariably achievers, with the odd few who were not being able to be very proud of their music. I had to pull some dirty strokes to fund it, but stuck with it. I am not a musician, but I was clever in who I listened to and who I trusted.
Our peripatetic teachers reckoned we had a better orchestra (about 40 strong) than any of the secondary schools she visited.
We used a drumming group to radically alter the behaviours of a number of nutters too.
Sorry for the drift.
CG