Experience, mostly.

I have a high IQ (so I'm told) and when I work at companies like these, they're managed like absolute hell. Metrics for miles and using technology rather than proper management to manage people.

Building social skills to identify intelligence is much more effective and significantly more personal. Yes, it can be gamed, but so can intelligence tests. The last one I took had 50% questions similar to, "If you rotate this paper 120 degrees and flip it, where does the dot end?" You bet your ass I took that test with a piece of paper in hand.