Pattern of practice
We focus on training one part (X). When we get that X right, Y may become wrong. We fix Y, X may become wrong again. We go and back forth until both X and Y are correct. Then we add Z on top of them.
3 parts: Fix two parts, move one part.
In the exercise of rotating horizontal, we must fix the middle (dantian). How to fix the dantian?
Use two parts (head and rear foot) to fix the dantian, move the front foot which is free to a new position.
Use and front foot to fix the dantian, move the rear foot to a new position.
Switch between the two feet repeatedly.
The is made of a series of little increments.
If we make the two side of a chest like two touching gears, we are using the central axis as the gap/space between them. it is the one of the 3 major choices for the gap. The other 2 choices will be the two shoulder-kua axes. The chest/torso can be one piece or two pieces.