Notes that are sharp I write the sharp symbol, notes that are flat I write the flat sumbol. I never write the natural symbol, and if a note is played with a sharp or flat multiple times in the same bar, I write the symbol each time (instead of just once). This works fine for me, because usually the
 only per
 son who reads my sheet music is me. And this system makes sense to me.... but is this a bad strategy if I were to share my music with other people?Like if I were to write something out for some horn players or a piano player or whatever, would this system throw them off do you think?
yes. accidentals last at least until the end of the bar. i always thought there was disagreement about whether or not they last until the end of the line. but they definitely last at least until the end of the bar, and you should not be repeating the symbol if the note stays that way within the same bar, and therefore you need a natural to specify if it changes back. and if it changes back right at the beginning of the next bar, probably use a courtesy natural just in case. if it's in different octaves i think the rules become a little more ambiguous and courtesies are good, i'm not sure of the exact rules when it's different octaves