The thing is, I fluctuate. Depending on situation, I swap my lead functions. I've realized this gradually, and only really started noticing when my ISTP friend (in particular, there have been others), commented on my mobilizing/change affecting behaviors. When I am relaxed, no pressing goals, nothing to work on, I am Ne dominant, constantly barraging my surrounings with what if and whimsy and loose connections.
When I am presented with a challenge, be it a lengthy lab, or group assignment, or something as mundane as cleaning the house, Te takes over. It is a seamless swap, something that I have only become aware of as I have learned more about MBTI, and all that jazz about cognitive functions.
Is this common? Is it even possible? I would say from personal experience, yes, but I don't know... I'm in ENTJ mode right now, btw. Te dominant, am studying for finals, so that kicked it in.