Ni is quite apparent in the INJs because Ni is in their ego, which means they consciously manage and process Ni. They actively seek to impart Ni information to others, seeing it as their natural duty, which comes with ease. Even if they are not imparting Ni, they consciously manage Ni information in their head. It is clear to them and others they provide great sage-like insight, and don’t mind appearing a bit prophetic and knowing. Their Ni tendencies are generally inwardly embraced.
The advantage of the fact they value their Ni is that they trust it in themselves, and are willing to directly reveal Ni insights in their speech, and though Ni insights are hard to explain they have developed the ability to impart them to others as best as they can. This conscious management of Ni makes its presence clear. Ni is naturally difficult to formulate, but many of them can make a pretty decent effort because their conscious ego really takes the time to do so. Ni is still quite intense because it is very strong, and can be overwhelming, but the conscious ego does its best to manage it.
The conscious ego also helps INJs speak of their Ni insights in a direct and overt ways to others. They may say they don’t share a lot of what their Ni comes up with, and this is true. That is because it is introverted, and also of course they know of some risk of ridicule from society. However, Ni is common in their speech, and they don’t mind the risk of allowing their Ni to express its natural tendencies of certainty of knowingness, even at the risk of others’ perception. They are still much bolder and braver about it compared to other types who have relatively strong Ni. The natural tendencies of Ni are directly and overtly expressed by INJs, unlike the INPs who do so indirectly.
The disadvantage is that Ni dominants appear to be taking Ni too seriously. If your mad genius ideas and prophecies are said in a serious and direct way, people might think they should send you to the loony bin :P. It then backfires, and the Ni insights of Ni dominants are then not taken into account by others, and are perhaps laughed at, unfortunately (Ni dominants are actually not necessarily as serious of their Ni as people perceive).
Types that don’t value Ni, including those with strong or very strong Ni like INPs, may see Ni dominants too confident in their inner perceptions and as psychotic (and willing to risk allowing themselves to be perceived as such by sharing their Ni ideas). They believe such information should be imparted via Ne instead (sounding more flexible and with all other options outside of the one Ni presents objectively presented) as to appear less intense and serious. Ni dominants actively repress Ne in themselves (Ne is their opposing function), and dislike excessive brainstorming of all the objective possibilities out there, especially when they “know” what will happen, or at least they believe they do. This is an advantage because they trust their hunches which can be remarkably accurate, instead of the endless list of Ne ideas, but a disadvantage because their might really be more possible outcomes than Ni suspects that may turn out to be worth considering.