The movement has several elements
A technique combines supports, legs, pelvis, trunk and limbs. In a slow exercise, identify their relationship rather than looking for a part of the body that is supposed to explain everything. A quick arm does not automatically indicate good organization; a spectacular rotation either. The instruction depends on the gesture, position and direction. Ask what should remain stable and what should change in the exercise being studied.
Compare orientations
Hanmi and shomen commonly designate body orientations encountered in kihon. Their exact implementation becomes clearer with school and exercise. On the same basis, compare a departure and an arrival requested by the teacher. Look to see if the foot moves involuntarily or if the shoulder completes the movement on its own. Comparison becomes more useful when you know which orientation you were looking for, instead of just judging the last image.
Do not enlarge a rotation as a matter of principle
Visible amplitude does not correspond to a universal measure of effectiveness. Greater movement may complicate the trajectory, reach or sequence. First look for an organization that is reproducible at a comfortable speed. In a movement, the pelvis does not necessarily rotate as during a technique performed on the spot. Keeping the same criterion in different situations can therefore produce an inappropriate correction.
An observable return
Film a slow test from the front then from the side, if the dojo allows it, and prepare a question. The goal is not to calculate an ideal angle on an image. Instead, spot a break: arm already arrived while the movement continues, foot readjusting after the technique, or trunk tilting. The teacher can then relate your observation to the specific instructions.
Check understanding
Do all techniques require the same hip rotation?
See answer
No. Path, position, movement and instructions modify the relationship between the different parts of the body.