I maintain that once you're able to play quarter notes in unrelated tempos with each limb, and switch between any tempo with any limb on the fly, you're truly independent and able to play anything from the New Breed...etc... easily.
And how can one disregard the exercise as being 'unmusical' entirely?
No-one knows how music will evolve - for example, in Bach's era, syncopation was considered unmusical, whereas now it is commonplace.
A band like Meshuggah who focus on polymetric groupings now has a wide following to the extent of pioneering their own subgenre, and having a band that plays in two or more unrelated tempos is just a logical extension of that.
In a word, NO.
The brain simply doesn't work like that. Mastery of one single coordination pattern does not automatically grant you mastery over similar coordination patterns.
I can play 19 over 2. That does NOT grant me ability to hear and feel 11 over 2. The ratio of 9.5 to 1 is what Im playing in the first case and 5.5 to 1 in the second. I had to earn each one.
There is no one alive on the planet, including Mangini and Minneman (who are past Lang on this stuff) who is truly independent. It's all an illusion of true independence. All of the patterns are relating to each other and to the overall pattern in some definable way. That exact relationship was explored by practicing as many permutations of notes against it as possible. The performance you hear is composed of those pre-practiced permutations linked together by the performing artist in a stream of consciousness. It's NOT just coming out of nowhere.
It's not true independence in the sense that entirely non-related patterns are not just flying out of nowhere.
And playing quarter notes against each other would only be scratching the surface anyway. What about coordinating actual musical phrases or cycles of phrases against those notes? Take your crazy quarter notes and now play one of them in a cycle of 11 and another in a cycle of 13 and another in a cycle of 46.357... It never ends.
I know what you driving at, and it is unrealistic. You would be old before you got anything accomplished.
Here's are some more "realistic" lifetime coordination goals:
1. To be able to play "Extreme Interdependence" cover to cover as Marco can. 1000-2000 hours practice.
2. To be able to play common subdivisions between any two or more limbs and be able to voice common subdivisions against them. This would take 5-10
thousand hours for example.
3. To be able to play all subdivisions from 1-20 notes per beat in the same way. This might take an ADDITIONAL 10-20 thousand hours. I have no idea. No one on earth has truly reached this point.
Im not kidding, you are looking at YEARS of woodshedding just to be able to get to #2 and that is nowhere near to the machine like concept you are discussing.
And none of the stuff in #2 will actually make you be able to play a better songo or make your jazz swing. BTW.
The idea of practicing some crazy technical exercise so that "normal stuff will be easier" has limited application. You get good at what you practice and play. If you never actually play songs and just play technical exercises, your song playing will suffer.
The reason why people are calling your concept "unmusical" is because it is. It's just pure math. There is absolutely no connection between the exercise concept and any song that anyone has ever played or sung on this planet. Ever. So your arguments about syncopation (besides being Euro-Centric) being thought of as unmusical during Bach's time are off. People actually use syncopation to create music.