When people say "grind leetcode" they don't mean it as a tool to get better at these kinds of problem solving. What they basically mean is that if you "grind leetcode" you have a better chance of being asked a question in these interviews that you have solved before and simply write down the solution during the interview.
If they're IQ tests, then why does doing a whole bunch of leetcode questions make me better at it? Isn't IQ supposed to be relatively stable throughout one's lifetime?
I've done hundreds and I have gotten better, but only to a point. At some level it's not pattern recognition anymore, just inspiration. And I'm not smart enough for that.
This one, for instance is expected to be completed in 30 minutes. I spent 2 hours on it yesterday and failed most test cases. I'm a failure.
Do thousands then and get back to me. It's all patterns, this "inspiration", is just patterns, your just not seeing it yet.
Its true on some degree, that you need some intelligence, but I have a few close friends who are FAANG, they are definitely not the best developers I've ever worked with, only difference is they really really cared about getting into FAANG. Getting into FAANG was basically their life ambitions, so they dedicated literally all there spare time to it.
I dedicated a lot of my spare time to it in college (and after) too. What did I get for it? I make just $200k a year at the least impressive FAANG and literally everyone considers me to be a mental defective.