I don't think it's about learning very fast. You learn the technology as you use it. It's about having the brain to reason around problems efficiently. I work

I don't think it's about learning very fast. You learn the technology as you use it. It's about having the brain to reason around problems efficiently. I worked with someone who become senior & team lead after 2 years (and a really good one at that), after having done business PowerPoints for their entire working life. I link IQs test (in informal channels) and all the juniors who picked up development really quickly and become very effective, all have high IQ. If it were allowed, I would definitely use IQ tests in an interview setting. I think leetcoding started as a proxy for IQ tests (which could totally be, if people couldn't prepare on the subject) but nowadays it's just testing people's ability to memorise different cases and being comfortable enough with coding to be able to implement (and mix and match) them.