Despite the individual nature of adaptation there is no shortage of rules, declarations, and prescriptions on how one should do things and why. There is also no shortage of "scientific" explanations as to why you should do this or that, or not do the other. Often "scientific" explanations are sensible but that does not mean they are true. Almost always, they are not scientific either. One of the most valuable lessons I learned in science is that sensible post-hoc explanations are a dime a dozen. They are also meaningless. Unless you can predict the outcome with some certainty, you have no understanding whatsoever.
One reason for the success of all these rules, despite their shaky foundations, is that humans love rules. Humans like structure in their lives and they like to know what is expected of them. Kids grow up listening to their parents and finding out the pitfalls of not heeding advice. When they grow up, they substitute their parents with real and imaginary figures of authority so they can maintain their comfort levels.
Social species also admire individuals who are good at something. They try to emulate them to get equally good, or at the very least, to please their idols. Such social behavior is highly productive and a major component of learning. Learning works by imitation. Yet when it is too rigidly enforced it often falls short of expectations. And training is one such area where rigid enforcement often produces poor results.
Publications love providing rules. They do so because it helps them sell copies. People like to be told what to do, and they like to feel they get their money's worth. A top ten list is easier to produce, easier to digest, and sells more copies than good advice. Top ten lists have invaded all media to the detriment of information content. Readers are becoming consumers of rules. It is not good.
There are no rules as to what cadence you should ride, or what foods you need to eat, or how you have sit on your bike or lie in the water. There are things that don't work, such a cadence of 0 or 500, but apart from that, nothing much can be said. Some great cyclists spin like maniacs, while others are slow crankers. Scottish legend Graeme Obree developed two very different nearly optimal aero positions and set world records with them. The UCI rule addicts quickly disqualified him. They could not stand it that a non-professional, using non-conventional methods, beat everyone else.
The less people understand something, the more rules and advice they have. That is clear when you look at swimming. Fluid dynamics is poorly understood and requires supercomputers to solve even trivial problems. A human body is not a trivial problem. Furthermore, even in trivial cases, flows are often counterintuitive. But all that has not stopped swim "experts" from proclaiming wisdoms about total immersion, corkscrewing through the water, and other wacko ideas. They also charge big bucks for it, which has the unfortunate effect that some people think they have to be good if they are so expensive.
The limitations of rules apply everywhere. Some people can eat cheeseburgers while riding RAAM, while others throw up when they eat the wrong candy bar. Some eat fruit galore, while others suffer from diarrhea as soon as they start running.
The take-home message is that you need to find out what works for you. To do so it may be helpful to imitate others who do things well. However, if you don't make progress, don't be afraid to reconsider. Do what works for you, and once you find something that works stick with it. Always learn to listen to your body. It is the most important thing you can do. And remember that the stars have more leeway than you. They can get away with things, but you don't. So if Lance spins fast, maybe he can afford this less-than-efficient method and still win. Chances are, you can't, so don't be tempted.