Ni types are indeed the most spacey and least attuned to their surroundings, and that is because external perception (Ne/Se) is the weakest in IJs. Compared to INxPs who by definition live fluidly in-the-moment through their (Pe) extroverted intuition ((c)1998 Lenore Thomson), it's often either a curse or a blessing for INxJs that they prefer overcompensating for weak Se/Ne using functions they personally find more interesting: in other words, Se-inferiors find a way that works well for them. INxJs find that their external surroundings (Se/Ne) are indeed the most trivial and complicated aspect of reality to get an immediate grip on, and so as N primaries (like Ne primaries), their priority is to refrain from dealing with trivial difficulties of individual details and facets, and to instead focus on the big picture, but in contrast to Ne primaries, Ni is about leaning on universal truths and devising productive programs to more efficiently deal with P's go-with-the-flow life. INxJs are even better at reaching for careers that better fit these strengths, as Ne-quadras often hint at how the INxJs should just use Ne by seeing the world as shortcut information and to-the-point interpretations, making leaps and generalizations with incoming information, but Ni is just not interested in Ne. Se/Ni is about staying open to the moment (instead of the mind), while Ne seeks out answers in the environment and assumes its a puzzle, INxJs want to structure their moment like Se types do, understanding the details step-by-step, in order to take what they learned to their office and immerse into Ni, not trust leaps (Ne) which they deem as careless understanding with holes. That is not to say Ni is unimaginative, but exactly the opposite: Ni types really don't like to make predictions and assumptions of the moment, that is what external perception is about. It takes a lot longer to process details like this, but in the end it's much better for the Ni type to understand "the working process" itself (Se) than it is to abandon Ni and train Ne to read-between-the-lines, when Ni is what they're after. And that is because there's an Ni master plan at work.
Ni's job is to contemplate and map out the bigger picture of experience itself, and finds that treating individual fields and moments as separate nodes of exploration (Ne) is too messy, compared to a holistic approach to knowledge. There-in lies the very difference between Ni and Ne (if not simply 'Inward Abstract Perception' vs 'Outward Abstract Perception'.) INxJs have great mental strength amidst apparent weakness, with their primary function as the kind of abstract memory that reads between-the-lines of reflection itself, meditating and exploring key concepts and generalities of life and imagination, which leads to INTJs being able to come up with the most productive master programs which deal with Pe's go-with-the-flow, sensate life in a very different way. Programs, not plans. (Plans aren't very N-primary.) Sometimes an INTJ's type is so pronounced that Se stays fully inferior while they process their overall reality with a type of cheatcode that persistently obtains the upper hand through accuracy of the whole, in that it's no longer intuition, but the product of a previous intuition: a well-designed program on like a slow-perceiving computer, that makes up for speed by making bigger-stake gains on their opponent who's running out of stamina, as long as it remains "plugged in" to this source or method. Se for an INxJ often looks like a hazy cloud in the way of them snapping to, trying to react to the rawness of what they appreciate in the moment, but failing as the Se-valuers they are, always meeting an intellectual disinterest half-way through. They're able to tap into Se in emergencies when they need to, but it's the worst and they feel that mind-body disconnect one has with their inferior function. I know people have also mentioned about INxPs being weak at Se. But there is great irrelevancy there, because INxPs already have secondary External Perceiving. (This might be a mistype thing if you follow function theory. INxPs are the Pe moment-engaged types.) They don't need Se because their Ne is so strong. It would be like saying I really need good Fe. Think about it! INxJs have to use Pe only when the time is right! I believe that INTJ and ENTJ are the types that make the best computer programmers, and that is because programming is a very controlled J field where reliance on Pe has become obsolete. xNTJs collect helpful tools and concepts (Te) to master their overall internally imagined programs/ideas with (Ni.)
xNTPs are a lot better at honing and developing internal skill to deal with changing dynamic systems (Pe), as they're types that easily gauge the environment with natural, instinctual understanding (Ti.) Like Dr. House (ENTP,) INTPs are good in these intuitive environments that require going-with-the-flow and utilizing control and leverage through investigation and developing logical instinct. I don't think an INxJ brain is very trained in this "natural genius," because Ni's whole philosophy and mentality is of the planned armchair thinker: "I will take time and get in the zone to really ponder a whole field, as in life itself, much more slowly and with depth," and Ne is much too specific as it searches for brilliant solutions to specific things as they happen (as Pe, less philosophically), which is terrific for the Ne type. But Ni doesn't do this, it's worried not with the big picture of a situation (Pe,) but with the big picture of its mentality and being, as it seeks to understand its whole perspective and generate possible concepts from within. The Ni is the type to most often say "reality is too average and predictable," and through this disinterest in external perception, it comes to the point of my post that they then fail at external perception. It is not a function that grows or is used as much as others'. And that is how I can compare the inferior Se of INxJs, to the secondary Ne of INxPs. They are opposite functions of one another, where one (Se) saturates itself in the five senses, like enjoying a good thriller or atmosphere, while the other (Ne) peers behind the curtain of sensations and attempts to figure out and piece together those externals. INxJs do not deal with these Pe externals as often, they go inward into perception to find their intuition: broad non-immediate answers, unhurried by demands, answers that work as a general understanding for themselves, like how Si is of a concrete understanding. Sometimes however, a solution for an Ni type is simply "living in imagination," like for an Si type it is "living in the past," like for an Ne type it is to "read into everything and figure it out" and for an Se type it is to "immerse fully into now." Solutions can have very broad applications and don't need to be for specific problems.