I love this little sub-thread. I don't know what it is about piano in particular that brings out the nail-biting. You don't seem to get that with guitar for example. What I like is that there's a lot of concern-for-others visible, which is admirable. The place where it strays into misplaced concern though (kind of as usual in life) is where in some cases there's a disproportionate intensity of concern that seems to indicate projection of each writer's own unconscious issues. I will now proceed to probably project my own, but just keep in mind... Why should someone care so much how someone else learns piano or
how much piano they learn? And why should the 2nd someone care what the 1st someone thinks in the first place?
Mira, does it sound good, ¿sí o no? That's the only thing you need to ask yourself. If it sounds bad, try harder. (Or don't. Since it's for you and has no meaning except what you bring to it, and since it's near-worthless as a way to pay the bills, you're kind of free to do whatever. Maybe that freedom demotivates some people. That too is fine.)
The argument for a structured approach or formal lessons tends to be that it prevents learning "bad habits." But what's wrong with finding that out for yourself, i.e. finding out that you learned a bad habit by progressing to the point that you notice the habit is bad? And then you either live with it (as many of them will actually be pretty inconsequential) or work to change it.
I can even make a case that unlearning a bad habit is superior in some ways to never developing it. Because first of all, the way you reach "good piano player" status is always by passing through "shitty piano player" status, but secondly, an analogy: The way you mature to the point where you see that, let's say doing drugs (another bad habit for some people) isn't so good for you, is by doing drugs and then quitting, not by "just saying no" from the getgo. What the fuck does a Nancy Reagan type know about drugs? Someone who quits drugs knows all about it. Ah but the additional knowledge takes (or if you think in terms of maximizing piano throughput like some industrial process, it wastes) additional time. If your parents have you convinced that your survival depends on getting early-admitted to Juilliard by age 14, yeah that is gonna hurt you. You can't spare the time to do it "wrong" or even to question whether doing it is bringing you any joy in the first place for that matter. But if you're willing to wait until age 18 for Juilliard, that gives you another 4 years to unlearn the bad habit. Plenty of time. 4 more years of playing piano, which is what you were trying to do in the first place.