Many people seem to think that if a little of something is good for you, then more must be better. I call this type of thinking, linear thinking, and I am always amazed at how prevalent it is, even among those who should know better. Maybe it is a cultural phenomenon? We in the Western World, favor linear views. We have a linear view of history for example and we have a tendency to call more of the same, progress. That linear view is embedded in our religion too. God created everything and from there on it just "evolves," where "evolves" means advances in a straight line towards an optimum.
From a marketing perspective, linear thinking is powerful. It is easy to understand and marketing people emphasize the need to keep things simple. Humans, it appears, are not all that smart. Or maybe their smarts are reserved for special cases? Could it be they are just plain lazy and prefer simple stories? Whatever the cause, linear thinking appeals to people.
It is of course true that many things are linear, or have a significant "linear" regime. Our bodies for example try to keep many variables within a linear range. Engineers too like to make devices that behave linearly or have a significant linear range. It has even been shown that people engage in certain behaviors to linearize a non-linear problem. I remember a Science paper that claimed baseball players move in a certain way to straighten the path of an oncoming ball. That makes it easier for the visual system to predict where it will land.
And we don't just like to think ahead in a linear way, we also like to extrapolate backwards the very same way. If a lot of something is very bad for you, then a little must be somewhat bad.
Experience however, has shown that this view is severely flawed. In most cases, moderation is best. Too little of something is no good, but too much of it is not good either.
These are good things to remember when training or preparing for a race, or enjoying a glass of wine.