I've played bass for...um...well, quite a few years. Only ever used chord charts. Never had read in bass clef. I decided that I wanted to be able to read; started using online tools to learn notes and rhythm. I've been working for the last day or so on an exercise with nine lines of music, low G to C on G string. Today I played it by sight @70bpm. It's an easy piece, all quarter notes and no sharps or flats. And I am still making mistakes, but I know when I'm wrong. I am making progress.