This is actually a pet peeve of mine – students writing the letter names of the notes on their music. It happens so often. I do understand why students attempt to do this. Students are thinking that this is a short cut.
As a one off, it does make it easier to so called read the music, but I don’t think it is useful in the medium to long term. The reason why it is not helpful in the medium to long term is because it actually hinders learning to read the music. I have many students try to argue this point with me, telling me that it will help them learn to read the notes, but in my years of teaching, this has never happened.
Writing all the names of the notes on the music actually makes it more difficult to learn to read the music because while you are looking at a pencil mark naming the notes, you are not carefully observing where the note sits on the musical staff (or stave). So if you keep writing in the names of the notes, you will not become familiar with the way the notes look and you will progress to more intermediate level pieces of music and of course, the number of notes on the page becomes a lot more. This ends up making the task of learning what the notes are, so much harder because there are so many more.
I think it is so much easier to learn to read the notes from the very beginning, because in the beginning you are only playing a few notes and that as you learn more notes, you can keep up with learning to read the new notes. With enough time, your note reading skills can be so good that you can read just about any note you come across.
I hope it is clear why I am against students just putting in the names of all the notes. There is one more thing that I need to say on the topic – writing in the odd one or two notes in, on a piece of music is okay because it can be helpful when a person consistently plays a wrong note at a certain spot and it needs fixing. Usually when this happens, a piano teacher will write it in because they know that their student has already obtained a certain level of proficiency in read the notes.
I am not only against students writing in all the names of the notes, I find it irritating! Here’s the choice you have – you can either write the notes in or not write the notes in. I will never know what you choose, but at least you know why it isn’t a good idea and you are free to make your own choices.