Studying personality theory I've come to the conclusion the dominant and inferior functions are the only ones that truly help a person understand themselves and reach for a broader understanding of others personalities. The auxiliary and tertiary functions just cause people to act in a certain way to prove they're a certain type. (I've done it unconsciously on this forum before as well.)
For example... INFJ'S and INTJ's will act so different on the internet but in real life, they are so similar. Same goes for ENTP's and ENFP's. This is because they share the same dominant function that guides their life and perceptions... Fi/Ti sneaks in there, but since it's so unconscious and won't really aid the person in their understanding, why do we include it into the type? We all buzz around the lantern of life using whatever function we feel like using. Fi, Fe, Te, Ti... We all develop these whenever the hell we feel like. But it will never define who we are, it will only manipulate our dominant function for a bit.
I think it should start being like... I'm a [Dominant function]. Doesn't mean I'm this crazy extroverted/introverted person in my life, it means my understanding and perceptions come directly from my dominant. For example I'm not a highly emotional person anymore than an INTP, and I don't go around screaming my feelings. This just means I'm somewhat sane, not a Fi user. I'm idealistic, but come on.... Who's not?? Everyone is idealistic, it's narcissistic to say "I'm more idealistic than a Fe user because Fi is my auxiliary." Yes, INFP's/ISFP's are more idealistic, but that's their dominant function, so it's understandable and logical to say they are more idealistic than the average joe.
TLDR: I don't know because I went to a ramblefest, but the dominant and inferior functions are the only functions that permanently exist in our conscious personality. The auxiliary and tertiary functions exist only on the internet and in our minds.