The idea that human personalities and behaviors can be sorted into two simplistic piles or even a scale between two piles is just silly.
There's no predictive value to it- you can't objectively classify\quantify people's 'vertion' and then predict behaviors or outcomes based on those classifications, not even statistically from a large sample set because it's meaninglessly subjective.
People are complex. Someone might appear 'introverted' in a social situation they're unfamiliar with, but in a different setting my appear 'extroverted' because they're very comfortable.
And some will say "social interactions give energy to extro and take it from intro" but what the hell does 'energy' mean in that context anyway? If I go to a small party with close friends all talking about sci-fi I'll enjoy myself all night and feel refreshed, but I'd be exhausted after 30 minutes at a rave and need a week to recover.
And do people migrate between intro-extro throughout their life? In my 20's I felt compelled to meet and experience new people all the time but now in my mid-40's I don't really care and tend to stick to the people I know. Does that mean I turned more introverted at some point? That's why even as a personality scale it's nonsense.
It's all just Myers-Briggs for dummies, which is already for dummies.
The only way it makes sense is as a description of immediate behavior, not of a personality. Someone may be 'behaving in an introverted way' but saying that makes them an 'introvert' is nonsense because they may go somewhere else and behave in an extroverted way an hour later.
Impressive resume you got there ;)
But which of those studies can show me an objective, reproducible method to classify individuals as introvert\extrovert? And I'm asking sincerely. I'll accept being corrected that there actually are rigorous clinical descriptors and tests for traits of for introvert\extrovert, though that won't change my opinion of literally anyone outside of a clinical setting applying those terms.