Two of my biggest pet peeves from yesteryear, not sure if they're still taught...
1) Your elbow should be directly under the ball. This is utter nonsense; nearly every great shooter has their elbow at least slightly out. What's far more important is having a relaxed, non-tense body when shooting. I used to force my elbow in, causing shoulder tension that would lead to a lot of short shots. Once I stopped caring about how tight my elbow I was I became a significantly more consistent and better shooter.
2) On jumpers, that you should land exactly where you took off from (i.e. jump straight up and down). "Sway" and a slight jump forward is the way to go.
3) Toes pointed at the rim. As with #1, it causes tension in your shoulder and hips. Slightly angle your feet.
The three-man weave is fine as a warm-up drill. That's all we used it for in college. Get the blood flowing.