A better way to describe the difference is that we take different paths to the same destination..I think you're dead on accurate in this description of the general weakness of the N position. And let me be the first to admit that I'm not sure how to get around this sometimes. I guess my Te (my tertiary function) tries to run regular fact checks on my theories. For example, if I conclude someone is an asshole, it's easy for me to look at the facts to support my theory. But when I'm at my best, I try to periodically step back, look at the big factual picture, and see if the behavior I observe backs of my theory. When I'm not at my best, it's easy for me to let my theorizing run a muck.
As far as it specifically applies to my understanding of being an S and what this means, let me be the first to admit that I'm starting with the theory and then looking for behavior from my S friends that supports the theory as I understand it. That's why I'm upfront that I welcome S clarification. I know I'm still learning here.
Until a couple of years ago, I didn't appreciate how profound the differences between being an S and N were. But I've come to conclude that this is the most profound difference two people can have. It's not that being S or N changes the way we think. The way we think is pretty much the same for all people. Instead, being an S or N changes what we think about.
If I were to place an apple on a table in front of us and asked everyone to describe it, an S is more likely to say "round and red." An N is more likely to say "a fruit." There are literally thousands pieces of information any human being is exposed to at any given moment... far more than can be processed by our senses / brain. So we all make choices about what information to process first.
Thus, an S and an N can be in the exact same situation and take in radically different information because they focus on different things. This affects how all of our other mental functions play out.
Think of it this way: There is a chronological component to the way we think. First we take in information (S/N). Then we make decisions on the information we take in (T/F). So back to the profound differences between how Ss and Ns think... if Ss and Ns take in different information from the very get go, then doesn't it stand to reason that all subsequent steps will play out differently because the input is so different?