Yeah, then what? I hear you cry.
Well, nothing actually it might seem a simplistic thing to say but I have seen many riders with shoulders not matching those of the horse and the horse struggling to follow the movement.
Check your shoulder angle matches your horses, on circles, straight lines and laterally. In the photograph of the Spanish Riding School of Vienna, see how the rider is sitting as if he is riding towards the camera, when actually he is going laterally up the side of the school.
His shoulder/body position is completely in line with the horses.