http://www.intelligentboxing.com/nei-kung/re the importance of Nei Gung, abandoning the esoteric for a moment.... holding postures from 1-10 minutes and repeating full body coordinated martial movement 41-360 times each, is going to have better and faster results than daily routines like forms where the single whip is practiced less than 20 times in total. Commonsense!
I've also seen similar excercises in other TCC styles, they are usually considered inside the door methods. Sometimes they are practiced with high stances and done with minimal movement as opposed to deep stances and full range of motion, I think there is enough sports science today to suggest which method is more beneficial?
The trouble with TCC and its leaning on Chinese Confusian culture is that the most revered masters amongst the plebs are the 100 year olds, and they sure dont move now like they did in their prime, when healthy young people aspiring to be fighters ape the exact "perfect" movement of a frail old man..... well, its not long until they start hopping around from a slight touch!
Conversely the first time I learned Nei Gung excercises from Dan Docherty, I recall within the first cople of minutes my mind became perfectly focused on one thing... "Oh fcuk!, Oh christ! whens he going to let us change posture, my legs are going to collapse! oh fcuk! my legs!!!! They are fcukin shaking!!! WTF!!! I'm going to die on my feet!!! now I know what it means.... Oh fcuk...my fcukin legs !!!....... the pain!!! THE FCUKIN PAINNNNN!!! ......"
Along with 2 minute handstands on fists, 80 rolls X 3, 20 minute rolling thunder punches 180 per minute with 2kg weights, and other monotonously painful excercises they straight away develop intent at its basic most fundamental level - the fighter's "heart"! I find they are excellent for truely transforming students in to useful martial artists, and the great thing is they keep offering more and more lessons and skills the more you practice.
Practice the 12 yin nei gung for 100 days and breath and movement will be unified in all your movements, your body will be able to receive force and deal with it instantly - you can take the jump test . Practice the 24 Yin and Yang Nei Gung for 1000 days and the intent and movement will be fused, you cannot excape knowing your limits and potential of movement, you will know instatly how to counter and recover WITH power. Chin Na will be everywhere as twists and rotation will be integral to your every movement. Training properly, you cannot escape this result! After that the more you practice and the more experience with opponents the more you instantly understand your opponents potential and limits, even from his posture, you automatically take in all your immediate envirnoment having developed and trained peripheral vision to keep your and your opponents seven stars and your envirnoment in constant awareness. i.e. "embracing the one / unity" At this level the typical opponent starts thinking you are using magic...
Can people arrive at this level of skill through other methods? Of course, there are many paths, but I never met or heard of anyone doing so through handform! Its not esoteric, its basic commonsense, the more you practice the better you will be. having a daily routine of thousands of repititions of your most common martial movements, reinforcing your self awareness of limits and potential, traininig and syncronising rotations and twists, folds and expansions, gathering and issuing simply put,
will work!