Aloha kdefro,
Yes, the good 'ol "Hug the Tree" exercise... yes that’s one of many, many, many, qigong exercises that give the body benefit. Chunyi has chosen those exercises he's found to be the most powerful and simplest to heal one's body. Notice the similarities with it and the forming of Yin & Yang? That, combined with the Moving of Yin & Yang, do more for your healing than just generating Qi.
He'd say there's no need to add another exercise, if the ones you have are covering it.
Now if you’re really set on integrating a horse stance, go ahead and get into a deep one while doing the sword fingers or thunder palms exercise from Level II. I did this while working through a deep chest cold at last year's retreat. My wife was leading the morning exercise on stage in the morning and wanted me to give an example of a deeper posture. Lets just ay that it's a challenge to do that for a decent amount of time when you're at 100%...when you're at about 45%, well, that would make most of your martial arts buddies wince a bit.
Much Love,
Shawn
