What about those last four functions
Dr. Beebe calls those functions "ego-dystonic."
That means those functions do not come as easily or naturally to us, and we do not feel "normal" when we use them -- in fact, we feel like we're alien, not ourselves. When we access them, our ego says, "Who was that? That doesn't feel right. That's not like me!"
As a result, we naturally tend to be more deft and graceful at using our first four functions than our last four functions.
To take this understanding a step further, we may automatically dislike or reject persons who prefer to use our "ego-dystonic" functions. This results in the ever-popular "personality conflict," without anyone ever doing something provocative. (Sometimes I wonder why God "hard-wired" us for conflict this way, unless it's his master plan for forcing us all to move out of our comfort zones and learn adapting skills.)
It's useful to note here that the definition of "Type opposite" comes up for grabs with this model. The tendency has been for us to suppose that the opposite of an INFJ is an ESTP because the codes have no letters in common.
But the fact is that both codes contain identical preferences for the first four functions, albeit in opposite order. For an INFJ: Ni Fe Ti Se, and for an ESTP: Se Ti Fe Ni. See? Same codes, opposite orders. So it's common to see INFJs and ESTPs attracted to one another and getting along famously (many of them married!).
According to Dr. John Beebe, it is most difficult for people of the same primary function but opposite attitude to get along, and the greatest personal conflicts arise between persons of opposite genders who have the same dominant function but paired with opposite attitudes. Again for an INFJ: Ni Fe Ti Se, and now for NFPs: Ne Fi Te Si -- no matches anywhere! Also with STJs: Si Te Fi Ne -- the same mismatching.