"are you saying that once you work on your internal beliefs all your external mannerisms magically shape themselves up?"
Not magically, but yes. Once you have learned about who you are, your own insecurities, your own issues that are making you believe that you're even unattractive to begin wtih, you will have nothing stopping you. You won't be bound to what people think because they will never make you question your own worth. These supposed "Don Juans" who work on nothing but external superficial shyt and try to convince everybody that they are 'confident and alpha' are usually the most insecure and dying on the inside. Because you can tell yourself over and over again that you're the man because you got laid, but you know damn well that if you get rejected 3 times in a row that "confidence" (or what you mistook as confidence) goes out the window. It was never confidence, just an ego boost which was deflated when somebody else shot you down.
"Why not work on both at the same time and see a greater improvement?"
It's not going to give you greater improvement. "External game" is nothing more than misperceiving there is something "wrong" with you to begin with and trying to mimic with what YOU THINK makes attractive people, attractive. It's never about hand gestures, pecking, kino, 'snapping of the head', it happens on a level much deeper than you'll never see if we're too caught up in this superficial bullshyt. It's why Vin Diesel can nail (a lot) of chicks (not all) by talking with his hands and pecking like a hen the entire time, and Danny DeVito can be so far up TD's ass with his rules and never touch a girl. It's about maleness, and how in touch you are with your own. Period.
"Also, I believe that working on your external game with techniques and body language pointers is conducive to more immediate, short term successes, which give the positive mental reinforcement necessary for you to improve your internal beliefs."
That seems to be the foundation of your misperceptions. That your external end result is what should shape the inside of you. The problem is that you're letting OUTSIDE, EXTERNAL FACTORS which are out of your control, shape how you feel about yourself. When you do that, you are giving your control away to unpredictible outside sources. So if you get laid, you feel better about yourself. You get rejected a few times, you feel like crap. And you think that if you get laid enough times in a row, that you'll have enough "confidence" (which is actually just an ego boost) to be able to DEAL WITH a few rejections in a row. Why live like that?
Why not REALLY learn about yourself, and be comfortable with yourself, and dig deep to resolve your own inner issues that made you feel that you NEED sosuave at all? That way, when things happen externally, you know it's happening OUTSIDE of you and therefore should have no impact on how you feel about yourself. THAT is true confidence, and THAT is something very few people on this site will ever see because they are too preoccupied with learning rules and "theory" and trying to talk themselves up enough and blow smoke up their own asses so that they will stop being such a pvssy and approach a girl; instead of figuring out WHY it was ever an issue to begin with.