A wonderful discussion that, moreover, I hold very dear, but which I would like to expand to musical teaching in general: whether it be piano, violin, viola, viola da gamba, composition or whatever else; or even the entire spectrum of education.
The discussion, however, is so vast that it requires one of those Brainstorming and idea reorganization techniques that our literature professor used to make us use before writing an essay. Therefore, I will certainly be very prolix.
The first step, in my opinion, should be to attempt to establish the objectivity and subjectivity of certain choices made by teachers; that is, to understand whether their thinking regarding the solution to a problem is dictated by a subjective or objective reason. In this case, I must remind you that an objective solution is one that can be logically deduced, a logic which cannot be rejected by those who understand it. E.g., All phones have numbers, therefore, there is no phone that does not have numbers. This type of logic must necessarily be justified and accepted by everyone, and if even a single event were to occur where at least one phone did not have numbers, the entire theorem would collapse and thus cease to be objective. A bit like what happened with the hoax regarding neutrinos traveling faster than light (this demonstration would have destroyed all of Einstein's theories, which instead have been proven true and objective).
A subjective type of solution, on the other hand, implies that in a group of people there can be one percentage that shares that solution and another percentage that does not. Even if the percentage of those who share it is much greater than those who do not, this does not ensure at all that the solution of the majority is the right one.
Given that most choices—speaking for my own case—in the field of piano interpretation cannot be traced back to an objective type of solution since no audio evidence has reached us regarding how 19th-century authors played their compositions, we must rely on what the authors wrote in their scores; most of the time they were indeed very precise in their markings, and only a careful reading of the score can reveal the thought hidden behind the myriad of interpretations that can be heard all over the internet.
Common sense, therefore, suggests that we pay great attention to the greats, to their interpretations, so as to be able to bring our own thinking back to something that gives us the illusion of something with objective value.
By listening to more than just one person, in fact, one immediately understands how choices can undergo radical changes from one interpretation to another.
The choice of what to take and what not to take as a model, or anyway the decision to follow in a certain musical phrase, is therefore dictated by our personal taste, namely that "Platonic" form in the world of ideas that already exists within us but must be rediscovered through study and understanding.
Schumann, in his "Rules of Life for the Musician," reminds us that if we manage to interpret a phrase by becoming emotional, then we will also succeed in moving those who listen to us. An intelligent phrase which, in my opinion, should nonetheless take into account an individual's degree of sensitivity.
There are those who get emotional watching a sunset, and those who are like a stone and are not moved by anything. In music, therefore, the degree of sensitivity also plays a very important role in searching for a study path to follow.
In light of what has just been said, we can therefore say that each of us looks at the same thing with different eyes and with different intentions, thus generating different opinions. No one can look at the same mystery with the same eyes. In these cases, however, we cannot speak of objectivity or subjectivity, but it would be more correct to discuss "inobjectivity." We all notice that a color is yellow, but each of us recognizes it with a different shade.
This is how it should be in music as well. We should work to remain within the author's thought without renouncing our own taste.
Therefore, it is fine to listen to the opinions of others, to the masters who advise us; it is fine to listen to the greats, provided that they support the reasons for our "whys" and, above all, reflect our personal musical taste.