Fundamentals of Piano Practice

http://www.pianopractice.org/ , suggest a link change.

I read it a couple years ago and it completely changed how I approach practicing.

While writing it, I discovered that piano pedagogy had never been researched, documented, and analyzed properly

is totally wrong. There's a Piano Pedagogy group just in the Bay Area, and lots of books on it.

I was an Adult Beginner, which is sorta a Thing. My teacher had about 12 adult students, and we had separate recitals from the kids. The hidden reason for this is, you don't want to hear some 9-year-old kid who plays better than you ever will.

Almost all of the other adults had played as a child and given it up. Many teachers won't take adults like me because they have unrealistic ideas about how good they're going to be. The truth is, you are not going to be very good, and lots of people who are orders of magnitude better than you can't make any real money playing piano, because that level of skill is so common.

The interesting thing about how our brains work is: I could memorize effortlessly, but I couldn't sight read worth shit. There are other people who are the exact opposite.

Lastly, one thing they said really resonated with me:

The first thing that must be done is to eliminate the habits of stopping and backtracking (stuttering), at every mistake. The best time to develop the skill of not stopping at every mistake is when you begin your first piano lessons.

OMG, in the recitals there was one lady who just had to play every note correctly, no matter how many times she had to try. She stopped at every mistake and "corrected" it, until you wanted to scream at her.

Now, my wife is completing her education degree and I see a lot of this approach being implemented in K-12: identify and focus on weaknesses; use your strengths to enhance your weakness; spend time on the big problems; balancing holistic approaches with concise methods, etc. All seem obvious and yet I didn't have a single teacher in music or otherwise suggest any of them to me.

This isn't so much of a problem if your intention is not playing professionally. Learning easy and intermediate pieces is a lot of fun. Also making your own music using a MIDI keyboard and a DAW.