4. Play for the other students of your teacher, a bit more stressful, but often very helpful.
In university we did this on an regular basis, every two to three weeks. All piano majors would gather in a room and play for each other. There was no academic merit or penalty based on how one played. The only requirements were to show up, listen to everyone else play, and play the pieces one was currently working on. Discussion was optional, some people liked the feedback, others not so much. The idea was to simply play, not to present polished performances. If the piece wasn't memorized, no problem, just use music. If you were working on a section of a very long piece, then that is what you played, no need to plow through the entirety of a 40 min concerto.
Very often things fell apart, but that didn't matter as it happened to everyone. This was probably one of the most valuable lessons to be had. Things fell apart when put in the situation of playing for others, and there was no penalty because of it, only the benefit of learning and self teaching. One learned the parts of the music that needed more attention. One learned how the pressure of public performance could affect one's music making.
As a result of doing this activity so frequently, the novelty and fear of a piece falling apart wore off, and people began to focus on the teaching and learning aspects of these gatherings. A lot of the times the lessons were non-verbal. It was more about what you learned about yourself than what someone else thought of your playing. The professor didn't really comment publicly about any criticism on ones playing, that was saved for private lessons. It was more about words of encouragement, introducing pieces with some random facts, and maybe telling a joke to calm nerves of some people.