I don't kick the tail around, I'd say I've done the dynamic skidded turns without flexing the board but then again when I'm riding I don't really think about my legs at all.
IMO, you should be constantly focusing on board performance and lower body movements to help you control your turns and which promotes good posture and form. I have found that at one point, your shoulders do what is necessary without you thinking. Unless you are going for a level test, you should have a quiet upper body that requires no thought at all no matter what type of turn you take. In a level test you want to think more because you dont want to fuck up.