But how people bring out those definitions when applied to the observable traits of those around you is more important. They do still need to adhere somewhat to the functional descriptions though, or else it just becomes a mash-up of interpretations ending in the theory being pointless.
I think books help a great deal however, although this might just be me, but since reading Lenore's book and Gifts Differing and even a bit of a foray into Jung's Psychological types, ive realised that all of the descriptions of the various functions are just tendencies id already been observing my entire life, it merely gives name to traits that are readily observable.
But it is done in a concise and fairly understandable manner, at least that's how I see it. As a young child I noticed that there were certain types of people in terms of their actions and mannerisms, but this was too generalised for my tastes, so as I got older I started to see things in a more individualistic way, by about 9 id already started working on my auxiliary function, (this was long before id read or even heard about this theory of course), but I recognised a problem in my communication with others and I realised that the only way to bring this out was to interact with others, to gain a better understanding of how to align myself with someone elses point of view so that I could then show them mine.
The only way to do this was with physical interaction and experience, there was no escaping it. So that's what I did. Years later I found out about this theory and read up on the cognitive functions, only to realise that id already been taking a beneficial route without realising it.
However the books helped focus this, helped me understand it and lead to more interest in psychology in general.