As a tutor, I'm first to say I cannot do anything to improve how a student performs. I've held many sessions where all my demonstrations and discussions have been ignored. I am not very happy listening to a parent's tirade of why I am not teaching their child to play. Once, when I asked how often the child practiced at home, the answer surprised me ... but explained more than enough. The answer was: "Never! I do not want that noise in the house!"
I'll just leave it, that the way the choir is directed in most churches, I'm not soloing on trumpet, and in some not even singing with the choir. Once when I was singing the tenor part, the choir director called me out ... the choir had been just singing in unison, yet the song was written in the hymnal for 4 part harmony vis SATB.
I really chuckle when the choir director is out of synchronization with the organist. Or ... is it the organist who is out of synch?