http://www.darionardi.com/functions.html

The problem I have with this – and one that Nardi has talked about – is because we’re all living through our own functions (consciousness is derived through it) one can not fully quantify development or even a full use of the trait because volition is not separate from bias.
I prefer to use his lab work for a guide, it’s empirical and it makes sense.
MBTI stops making sense when everyone has to have an order to their functions because not everyone is prototypical, if anything they develop neural networks and relief functions that may mimic a certain pattern, but not to the exactitude we’d like to think.