I don’t know about other practitioners, but I was always taught to utilize certain hand positions in all stances. Even in the Wuji stance at the beginning of Taijiquan, my hands had to align with certain accupoints in my legs. The hand and arm positions in conjunction with the legs, help to stimulate and regulate the flow of qi through the various meridians and extra channels in the body. While I am not an expert, there are a few examples I can share from Taijiquan. In the standard horse stance, one example is when the hands are held in the “embracing the tree” posture. This is suppose to be an all around tonic for many chronic ailments such as gastrointestinal, neurological and respiratory disorders. An example of the bow stance is “single whip.” This strengthens the cerebral cortex, nervous system and circulation. The empty or cat stance in conjunction with hands in “needle at sea bottom” strengthens the lower limbs, kidneys, lower back and relieves hypertension. I haven’t heard any specific health benefits attributed to the “golden rooster stands on one leg” posture other than helping to develop balance and strengthening the legs although I suppose it helps with the nervous system and circulation as many of the movements seem to do. I don’t have any information about the other stances you listed, perhaps some others can relate from their experience.
Interesting simplification.
One would think it could be simplified as :
Simply look at a stance and consider centering and the posture and judge how the Qi could be one rooted and generated, secondly passed and controlled.
Also note as different schools do stances different their effects could differ as such.
As an example any stance would build local qi in the area that would accumulate and the dissipate throughout the body thus the benefit. Then some stances are for rooting allowing could control of the centre, horse stance and the level stance come to mind here, for relaxing sufficiently to ensure good Qi generation in either of the 3 main energy centres (including the Dan Tien).
The back is important in realisation of Qi having to flow nourishing marrow. Rooting for activating the Qi expelling centres of the feet etc..much other examples…but almost anything could be looked upon in this way.