Two years self-taught and completely flat — did lessons actually unstick people, or is it just accountability?

Six years self-taught, then three years with a teacher, so I can compare directly. The thing that changed was not repertoire or theory, it was that somebody watched my hands and told me things I could not possibly have noticed: that my wrist dropped on every descending run, that I was pedalling with my ear instead of my foot, that I practised at one tempo and called it practice. First six weeks were mostly unlearning and felt like going backwards. By about month four I was learning new pieces roughly twice as fast as before, and that has never gone away.

Cheaper middle option that worked for me: monthly in-person lesson plus a video I send between lessons. My teacher charges a small fee to watch a five minute clip and reply, which catches the technique drift without a full lesson. Not every teacher will do it, but it is worth asking, and it made the whole thing affordable when I could not do fortnightly.

Fortnightly is genuinely fine for an adult who practises daily, and I would argue better value than weekly at your stage. You get two weeks to actually do the work rather than turning up having half-done it. What you lose is momentum if you are the kind of person who needs a deadline. I did fortnightly for a year and a half, moved to weekly for three months while learning a hard piece, then went back.

Going to disagree with the enthusiasm here, mildly. A bad teacher is worse than no teacher, and there are plenty of them teaching adults badly because their real business is children doing grade exams. Before you commit, ask for a single paid trial lesson, bring the piece you are stuck on, and see whether they diagnose something specific in the first twenty minutes or just hand you a book. If they cannot tell you something concrete about your hands that day, keep looking. It took me three teachers to find one who was interested in an adult with weird self-taught habits.

The accountability theory undersells it. Accountability is why I practised; the teacher is why the practice was worth anything. I spent my self-taught years playing pieces from beginning to end and calling it practice, and my first teacher banned that outright for two months.

Two years is exactly when the self-taught ceiling shows up, because the things holding you back are now invisible from the inside. Pay for four lessons, not one. One tells you nothing, four tells you whether the person is any good.