Dude, I've been playing jazz guitar for a very long time. One thing I can say is that IF you do screw up just riff on the mistake and make your way back into the groove. Seriously man, it's jazz. Just improv for a bar or two and then hop back in. As long as you stay in key the screw ups don't matter......unless you are a studio musician in that case you will have a chair thrown at your head if you aren't on point for ever note and tempo change lol. But seriously dude I've played some pretty big shows and trust me, no one in the audience is going to hear you hit a sharp or flat note that's out of line as long as you own that -blam!- up and riff off of it.