As a stupid fool responding to the yin yang exercise neigong routine and their utility, they are excellent for allowing its elements to "permeate" the actual form repetition over time.
That being said, it is impossible for most people to tell or even see the breadth of its benefits in an individual so in the long run it has the appearancve of uselessness for the observer. The one who possess it within his person is the recipient of good fortune and wisdom. Genetics and lifestyle choices are variables that many refuse to see or acknowledge in this wholistic paradigm.
Again, the yin yang exercise are beneficial alogn with those routine that approximate its usefullness