I'm not a fan of how the cognitive functions are stacked. There's just something about the rigidity of it all that I don't believe in. As an INFP, I do use Fi more than my other functions, but I definitely don't use Ne more than I do Si. If I had to order my functions in the order I use them, it'd be:
Fi > Si > Ti > Ne > Se > Fe > Te > Ni
function ordering isnt about how much you use them. the idea on dom and inferior ordering is that opposite of what dominates is repressed and works mainly unconscious. dom/aux idea is that the aux supports the dominant, so they sort of link together, for INFP its Ne feeding info for Fi and supporting it. if those two functions were both same orientation, it would cause you to go into some sort of introverted loop(Ji feeds info for Pi normally, but if you feed info to Pi with Ji and also perceive from Pi to feed Ji, it would drive you crazy, since your Pe would be rather unconscious(in 3rd or 4th place)). and tert works the same way with inferior than dom and aux work together. since you got P thing going on in conscious(dom/aux), the opposite J thing is working in the unconscious(tert/inferior). also since inferior is repressed to unconscious(in shadow in jungian terms) since it goes against ego, you need something in between to sort of reconcile the conflict between dom and inferior.
you should think it like this sort of loop:
Pe feeds Ji, Ji feeds Pi, Pi guides Je and Je guides Pe, then Pe feeds Ji and it goes around and around.
also one of the most important things to understand about all of this is that introversion is basically taking away unnecessary info from external world and only taking in what seems relevant, so you introvert
from extraverted function when its about P working with J(INTJ sees loads of facts with Te, out of which he takes in with Ni only what seems to be relevant for the big picture, what is irrelevant, Ni disregards. INTP sees possibilities in external world via Ne and uses Ti to cut off the irrelevant). Ji and Je(or Pi and Pe) conflict if there isnt anything between them to sort shit out, how ever conflict is much smaller between aux and tert since there isnt so much repression going on and neither is too big on the ego, the conflict happens between ego and shadow(jungian unconscious, not 8 function theory bullshit shadow). extraversion is the opposite, putting an meaning to external world from inside. external world wouldnt make any sense if you wouldnt put a meaning to it from inside, it would be like putting a camera on computer, but no program to process what is it that the camera is showing to the computer.
that 8 function theory is just silly, cba to go into that right now, but the 8th function for example is what happens when dom and inferior conflict, jung calls this sort of "dialogue" between ego and unconscious a transcendent function and from this conflict comes out the reconciling third to solve the conflict and give you new way of looking at things. in INTP this conflict between dom and inferior looks like Fi(which according to that 8 function theory is INTPs 8th function), because its conscious Ti introverting from Fe thats working unconsciously. but thats whole different story.
oh and the thing you should understand about this ego(what you are conscious of) and shadow(what you are unconscious of, but has an effect on you), is that shadow shows itself as instincts and projections, so you can come conscious of what it says and its effects on you, but if you understand what it really means, you need to pay really close attention to it and develop something in between.