Nardi's temperament types

It is very generalized. The pattern for each cognitive function is a generalization. There is no precision to the fluidity of the human mind, just tendencies and similarities. How each individual is similar to the pattern is where we can determine commonality. The brain maps are like fingerprints with activity levels in various regions being interestingly individualized. Each subject is unique, but some are more unique than others. Age, skills set, and Enneagram seem to be the most obvious influences, but that's not the only way in which subjects differ within any given type. What unifies them is the overall way in which their minds interact with themselves.

To get function specific, this data and these patterns are much better discerned with Te than Ti. It's a big picture relationship and relative tendencies, not clear details and binary rules. But, once the data is compiled, averaged, and analyzed, the definitions present themselves.

I think the best analogy would be martial artists and their movements.  Sure, we can divide them into left and right handers, but when we analyze the intricacies of their movements, we start to see a host of subtle distinctions.  The end result might be a punch, block, or kick, but how each subject punches kicks and blocks is a reflection of not only the style (type) they were trained in, but how long they've practiced that style (and learned more moves while refining the ones that are central to their style), and their own individual physiques and proportions.  Even within the same styles, no two practitioners are going to have the same movements on a microscopic level... and as they advance in skill and mastery, each style will begin to resemble other styles that have common areas of focus.  By the time true mastery is achieved, the ability to determine left from right handers is almost impossible.