Regarding the idea of extroversion vs. introversion, I had found an interesting article talking about how "creative" people are more likely to exhibit both introversion and extroversion in their lives as opposed to anyone else. According to the study, "creative" individuals, consisting of professions such as actors, comedians, and musicians, are prone to display both personality types "simultaneously," while the everyday person is more likely to exhibit either one or the other at one time. This stems from the notion that those considered "creative" display extroversion when on "center-stage" and introversion when behind-the-scenes, both within the same time-frame.
I can personally relate to this article, as I feel that I too exhibit both introversion and extroversion at given moments in my life. The concept of displaying the two "simultaneously" may seem questionable to some, but I believe it makes perfect sense for those whom this refers to. I am comfortable being sociable and full of octane as an extrovert as well as being quiet and deep-thinking as an introvert. I believe that both can be equally important to the functioning of a person, although it does not apply to every single person, nor should it.