As we get older, we hopefully realize this is a weakness and sometimes we need to use the functions we've ignored, so we begin to explore other ways to view things... and thus develop our inferior and the other functions. (This is a frightening process, though, because it's like starting from scratch and we feel unsure and clumsy with these relatively unused functions... and it's so tempting to stick with the ones we HAVE developed.)
So for example, an SJ person might look at their mouse and say, "Um, it's a mouse." Because that's the mode they're in - the tangible, practical value of something. But if you instigate some brainstorming with them and they shift gears, they are very capable of using Ne and thinking of all the things it's similar to. still, they'll be "rusty" until they practice this a lot.
An NP, though, will look at that mouse and see it as a mouse, PLUS lots of other things all simultaneously. I look at mine right now and see a computer mouse and a bola and a real mouse and a grappling rope and a rip-cord and a pendulum and a clown-face (because it's all white, with red on the tip/nose where the infrared part is)... well, the list goes on and on. I'm never confused that it's really "just a mouse" and that's how I primarily use it, but I find it boring to just see a mouse and like the feeling of imagining all the patterns it fits with, giving me more ideas to think about.
So yes, you can use ANY of your functions... but you are going to usually start with a perceiving function (S or N) and a judging function (T or F), one of them used in the extroverted realm (external world) and one in the introverted realm (internal world), because we need to take in information, evaluate it, then act upon it somehow. This covers all the bases and keeps the main functions from interfering with each other.