The US military has done intelligence and aptitude testing for 100+ years.
Three IQ tests that I took at ages 11 and 20 are within 2-3 points.
I firmly believe in testing, categorization, etc.
Most people will test closely over long times(repeatability)
These 5 categories are not "arbitrary," but instead the result of study over fairly lone timeframes.
Th e categories themselves, predate using them for political classification.
Whether any of it means anything is something else altogether.
I test very high in IQ because my thinking process is based around determining options, and taking decisions within a rigid structure. Each option chosen results in a decision, which leads to more options, more decisions, and etc - Basically 'critical path' thinking... A grand process of elimination, leading to a result. And because I can build that structure out, into the future or beyond the circumstance, it becomes self predicting...
It works well for me - But I am also quite aware of my limits - And there are more fluid forms of thinking that in some instances would serve me better, that I am incapable of performing.
Most people can function in a more seat-of-the-pants way, falling into opportunities by chance, that I will never see because of my brooding. That is offset, because I make my own opportunities by design, but which is smarter is a question for the ages.
One seat-of-the-pants guy that I am thinking of particularly is my best friend. He has a quick wit, but he never has scores well in IQ tests. Low average, at best. We work very well together - I am far-seeing, and he is day-to-day, and never the twain shall meet. But put the two together...
But as a matter of intelligence, if asked which of us is smarter, I would be hard pressed to take that prize. His way is different than mine, but in no way less valid.
And that is the problem with setting standards. That which doesn't fit them is often valid anyway, and may actually perform far better than the predictable standards can assume.
JMO