Flying High,
Excellent point re: changing our peronality over time. We can change certain aspects of our personalities. Over about two decades two out of the four of my MBPTI changed. Some of that was intentional (I was ignoring my Intuitive side, relying on my Sensing side too much. What can I say, I'm (was) shallow). Some of it was likely natural. I was much more introverted when I was younger, likely as a result of nature/nurture, including my time in the Borg. I've become much more extroverted since that time. The MBPTI is also only one tool for understanding people; it wasn't meant to be a stand alone evaluative or analytical tool, including for hiring/job placements and promotions.
Kiersey's books have been used widely, as I mentioned previously, by counselors. Some marriage and family counselors make it required reading. Please Undertand Me and Please Understand Me II, though not perfect science, are very accurate. I was very skeptical of the MBPTI and Kiersey before I began looking into it. I used Kiersey's books to understand my chldren. My son is an Artisan; I'm a Rational. Sometimes I think he is from a distant planet!!! Kiersey explains that is normal.