If this is for jazz/pop, use your ears. Listen to the song, and develop your playing-by-ear skills. You will learn the songs much faster (and become much more adept at playing musically) than just staring at the page. Most of the jazz/pop tunes I know were learned by hearing them, and all of the rock/country/r&b material I play were learned sans written music. When you get out into the real world (commercial, not classical) sheet music is not very common, so a professional career in commercial music just about requires you to be capable at playing by ear.