Sheet Music Gets You Started
When's the last time you've seen a blues harmonica player read sheet music on the bandstand? I've never seen it. Though it's very helpful to use notated music/TAB to learn new material, use it only long enough to help you figure out what to play, and which technique(s) to use to present it, and then don't look anymore. To memorize as you go is to internalize your material and be able to focus on its rhythm and presentation. Also remember to take out your favorite lick from that day's practice and spend the last 1/3 of your practice time and apply it to the Chorus Forms.