These are true and I agree to this, that's why I said both first and third instincts are neurotic on my prior post. They are neurotic in different ways though, hence one is first and the other is third. You cannot balance someone's neuroticism with a balanced use of it. If something is on the extreme end of the spectrum, its dual is on the opposite extreme of the spectrum not in the middle of it. Ofcourse saying that we can say both extreme ends are unhealthy and middle is healthy, however, that doesn't change the relation of those.
We can say every kind of filter, cognition style is there as a survival mechanism. What is wrong with us generally dictates our relationships more than anything else.
Why do you think first instinct cannot help last one? Can you explain by giving an example?
I don't know @inumbra, I get pretty fixated on my DS function as well
As I said I think both first and third instinct are neurotic in a complementing way. However, that neuroticism doesn't alone make this duality a duality. If opposite stacks get dualized in other words, if they start to communicate with each other via using their second instinct, then they can push each other on the middle ground.
I see the second instinct as a tool to merge these different worlds together, hence each partner being more open to other person's view since it is transmitted in a way that they can understand.
For example, so/sp/sx's sp is supervised by so, hence that second sp carries some so info. Its dual carries sx info, since second instinct is balanced in both, they are more open to receive it via that.