I have been learning piano for almost two years now, making good progress. I have good knowledge of the different scales and their corresponding key signatures. When I learn a new piece, I usually find it easier to add with a pencil accidentals that are present in the key signature in some confusion-prone places.
For example, in the key of A major, I sometimes add a sharp to a C note.
My question is, how detrimental is it to my ability to learn how to play pieces of different keys? The up side of what I'm doing is that it's easier for me to learn the piece and read its notes.
However, I'm wondering how bad of a habit it is, and whether I should lose it completely and focus on mastering the different keys before I move on.