You only need to invest in a couple of sessions to realize the importance of music lessons. You’re probably playing your instrument without technical knowledge of music theory. You can craft your own pieces with self-taught skills, but there’s only so much you can do on your own. You’ll crave for proper instruction sooner or later, especially when you’re aspiring to play like a professional. You’ll need a thorough understanding of notation if you want to play a Tchaikovsky piece; you’ll spend months on a part if you learn it through trial-and-error, when you could just as easily learn it within a week if you use standard notation. Your guitar, piano, or flute should be played according to the music sheet notations, especially if you’re part of an ensemble.