I teach at university level and I take private students, so you would expect me to tell you that self-teaching does not work. I am not going to, because it is not true — and saying it would be a way of selling lessons rather than answering the question.
A great deal of learning the piano can be done alone now, and done properly. But not all of it, and the part that cannot is specific enough to name. Once you know which four things you are blind to, you can cover them deliberately instead of hoping.
What you can genuinely do alone
Reading music. Entirely. It is a knowledge skill: the page tells you whether you were right, immediately and without opinion. Adults learn to read faster than children do, because counting, patterns and symbols are already familiar.
Theory. Key signatures, intervals, chords, why a piece goes where it goes. All of it is learnable from good material, and adults tend to enjoy it more than children because they want the reasons.
Rhythm and counting. Mostly. Counting aloud is self-correcting — if you cannot count aloud and play at once, you are going too fast, and that is a test you can administer to yourself.
Learning the notes of a piece. Absolutely. This is the bulk of practice time, and it needs patience rather than supervision.
Building the habit. Which is, in the end, the thing most likely to decide whether you are playing in a year.
The four things you cannot diagnose in yourself
Every one of these has the same shape: it is invisible from the inside, because you hear and feel what you intended rather than what happened.
1. Tension. You cannot feel your own tension until it has become pain. A wrist that drops on the hard bar, a shoulder that lifts, a thumb clamped against the side of the hand — these are the most consequential faults in adult playing and the least available to introspection. By the time they announce themselves, they are months old.
2. Your own sound. You hear the sound you meant to make. Sitting at the instrument, with the keys under your hands and the intention still in your head, you are the worst-placed listener in the room. A recording of yourself is a genuine shock the first time, for everyone, including professionals.
3. Unevenness. Almost every beginner plays the fourth and fifth fingers more quietly than the others and does not hear it, because the brain helpfully corrects the volume of notes it expected. This is not a flaw in you; it is how listening works.
4. What to do next. Not what to learn next — a good course sequences that. What to do: whether a passage needs slower practice, separate hands, a fingering change, or leaving alone for a week. A teacher's real value is rarely the explanation. It is the diagnosis.
How to cover the gap without weekly lessons
Film yourself once a week, one minute, and watch it that evening. Phone on the music stand, roughly at keyboard height so the wrist line is visible. This covers a surprising amount of items one and three: a dipping wrist and a lifting shoulder are obvious on video and invisible in the moment. Watch it the same day — if you wait, you will be watching a stranger.
Listen back with your eyes shut. Play the audio of that minute without watching, and listen for one thing only: are all the notes the same weight? You will hear the fourth and fifth fingers disappear. You cannot hear it while playing; you can hear it on a recording almost at once.
Use a real course, in order, rather than a playlist. The ordering is most of what a curriculum is. Jumping between videos by topic gives you gaps you will not know you have — and gaps in the first year are exactly what produces a plateau in the second.
Get outside ears occasionally. Not weekly. A handful of times a year is enough to catch a fault before it sets. That is why I read and answer recordings people send me, and why it is free: the point is that a small physical fault caught in month two takes a minute to correct, and the same fault caught in year two takes a season.
What I would say if you asked me straight
Teach yourself. Use a proper sequence, do fifteen honest minutes a day, film one minute a week, and send it to somebody who can hear what you cannot every few months.
An adult doing that will get further in a year than most people with a weekly lesson and no practice between them. The lesson was never the magic. The noticing was — and noticing can be arranged.
When it is worth paying for a teacher is a narrower question than the internet suggests: when you have a physical problem that recording has not solved, when you want to play something genuinely difficult, or when you have plateaued and cannot see why. Those are diagnosis problems, and diagnosis is the thing a book, a video and your own ear cannot give you.
If you would like me to look at where you are now, send me a minute of your playing. And if you have not started, the whole forty-one-lesson course is free and in order — begin at the beginning, not with the piece you want to play.