Since I owned a school of music with over 400 students my thoughts are; you can always learn something from a qualified teacher.

I studied guitar with seven different teachers. Each one added something different to my inherited ability.

When I took trumpet lessons from my old Italian uncle I did not get to touch the trumpet until I went through six months of sophagio (Terrible spelling) That is a music reading course on timing. You said the notes and held them for their duration. (Do Rey Me Fa Sol La Di Do) Never had a problem reading music after that.

Six months of trumpet lessons without touching my trumpet aaaaaaaaah!
John C.