Masters of Merit / Practice That Changes You
Repeating what you can already do is not practice
Most of what people call practice is maintenance, and maintenance does not move a level.
Sit and watch an hour of ordinary practice and you will usually see a person doing the parts they enjoy, at the speed they are comfortable with, from start to finish, several times. It is pleasant, it is honest work, and it changes almost nothing. The passages that are already fluent get more fluent. The two bars that fall apart get played through at speed, badly, on every repetition, and are therefore learned badly on every repetition. The hour has been spent, the level has not moved, and the person leaves believing they have practised.
Practice that changes anything looks different and worse. It concentrates on the part that fails, isolates it until the failing element is small enough to control, and stays there long past the point of interest. It is uncomfortable by design, because comfort is the signal that the work has drifted back to what you can already do. It also produces very little that anyone would want to hear, watch or eat, which is one reason it is rare: the practitioner spends an hour on a thing nobody will ever see as a distinct achievement.
The test is simple enough to apply honestly. At the end of a session, ask what specifically you could not do at the start that you can do now, however small. If the answer is nothing, and the answer is nothing on most days, then the session was maintenance. Maintenance has a place, particularly around performance or delivery, and it should not be confused with the work that moves a person forward. Confusing the two is how a decade of diligent effort ends where it started.