All Chinese martial arts schools do stance training. It is often considered the most important training for developing a gongfu foundation.
I estimate that I have stood still for on the order of 6000 hours, probably more. The longest period of time I have held a single stance is 6 hours. My shaolin students learn and train the following stances: Horse, Cat, Falling stance, Bow'n'arrow, Monk, cross leg or t-stance, and natural step (ziran). Every movement in taijiquan should be held, and basically the same goes for xingyi and bagua.
Wang Xiangzhai, the highly influential 20th Century founder of Yiquan said quality stance/stillness training was what all great Chinese martial artists have in common.
My own experience is that deep stance training is more effective than stretching and high kicks for re-making young Northern Shaolin students bodies so that they have a bigger range of movement potential. This is sometimes called, "getting the qi in the channels."
While in my twenties, an hour a day of low stance training initially made my thigh muscles and shoulder muscles bigger, but as time passed and my alignment improved my muscles got smaller and smaller. This is sometimes called, "qi going into the bones."
It's true, my muscles got smaller. My alignment improved and along with it my ability to issue power, to connect (integrate), twist, and pulse (open/close). Believe it or not, I got weaker. Not lazy or deficient but muscularly weaker and functionally more sensitive.
As time has passed I feel my use of higher stance training (still an hour a day) has helped develop more freedom and naturalness in my everyday movement. This is sometimes called, "Writing the Classics (jing) on your bones."
Stances on one leg, both high and low, are essential for developing kicking power, and are of course great for balance (in a future post I'll explain the physiology as I understand it.)
There is a ton more I could say about this subject and probably will in future blogs. I encourage readers to add your comments about what role stances have played in your training. In your opinion, what does and what doesn't stance training achieve?