ENTJs when they need an answer will pause a moment in their headlong forward progress and reflect. That would be Ni in operation, and heavily focused by Te. Together they decide what's best for the given situation.
INTJs when they need an answer would pause a much longer moment, days or months longer, going through a bigger array of possibilities--not necessarily more possibilities, more like to a greater degree of abstraction (and thus connection to other things). But the whole thing is still focused by some Te question. In the INTJ the pragmatic here-and-now aspect of it will get lost somewhat in favour of abstraction, I guess.
But still, for both, at any given moment it is very likely they are dealing with the kinds of issues or situations they prefer, and usually the obvious dealing function is Te. So when consciously called upon Ni doesn't have to go very far to find similar or related answers.
More Speculations:So, if an ENTJ stereotypically has a problem with thinking they know best about something, that would be more a function of their dom Te rather than aux Ni?
If we were talking INTJ, I'd say stereotypically thinking they know best is a product of faith in Ni. (You gotta have faith--if you don't, you're pretty much screwed because it does a lot more work than Te).
But if we're talking ENTJ, gotta remember we're talking about people who (a) use Te a lot and are good at its focus area, and (b) enjoy getting the actually physical process of the solution started quite quickly. Even if they somehow didn't find the right answer in (a), they can and will correct it fast in (b). They by experience and functional preference need and can have faith that they are right. So they have faith in Te+Se, and also, naturally, faith in Ni.
And all of this promotes miscommunication with NTPs (and NFJs), I guess because Te, the focuser, isn't unfocused. The NTJ doesn't, unless pressed, question foundations of decisions in the moment. Te+Se is more likely to say, well there's your foundation right there *points to the real world*. And if you're pointing an NTP at the real world, they'll start using Ne, not seeing the foundation for the possibilities. (And if you point an NFJ at the real world, they'll see a wholly different arrangement of objects and processes, not mechanistic between things but human between people.)