It's a weak proxy for general mental ability, but it's also a signal for high conscientiousness -- someone willing to spend a couple months studying to the test is showing that they have the ability to work hard on something over some length of time.
Why not bring back the civil service exams of Imperial China, then? Surely one's willingness to undertake extended study of the classics of Chinese literature, and to master a stylized form of discourse about them is also a signal of conscientiousness, isn't it? As a "bonus," this is likely to take far longer than the few months people spend practicing Leetcode.
When I was in grad school for CS, I recall talking to the dean of the department who said that his preferred approach for recruiting CS students would be to have them write a five page essay on any topic of their choice. Anyone who could write a coherent essay would probably make a good researcher. Unfortunately, he was never able to put this into practice - the university administration only considered grades and GRE scores.
Does grinding for months even work? The point of this post (and others like it) is that you can spend years doing leetcode without getting better. In comparison, I score far below most of my peers on conscientiousness but I find leetcode style problems easy. I'm a terrible hire in lots of roles because most companies' problems are boring. I have a history of getting bored and quitting. But I sail through these interviews.
If conscientiousness is what companies are going for, I think they're still interviewing wrong.
I think it works to some extent. There's a limit to how much you can get out of yourself, and a lot of dumb luck involved in getting interviewers who are actually reasonable.
In my case, when I grind those dumb problems I quickly go from needing 45+ minutes to implement a working sort function with file I/o to banging it out in 5-10 minutes. I dunno if I'd ever get good enough at those problems to make it into Google unless I got lucky, but I've gotten offers from the other FAANGs over the years
The whole thing is pointless, though. If a junior engineer asked me for advice, I'd tell him to get whatever job he can and work on saving money/building a startup in his spare time.
Grinding for months to get into Google is so soul crushing, and working for any big company is just awful in the long run compared to being independent
I think leetcode is just like anything else you practice - in order to actually improve you need to practice the right way (or in the OP's case, with the right state of mind! Being burnt out is a fundamental problem which needs to be fixed first!)
I started out thinking I was pretty smart but got blasted by a fairly simple question on my first screening interview. I started looking at random leetcode questions but that didn't really work - I soon figured out that I needed to learn the concepts one at a time. I think that is the way to do it, get a list of general topics, learn about it, then practice just those questions until it clicks.
It's also a weak proxy for high conscientiousness. More often than not, it's actually signalling someone is young enough to not have other commitments, contributing to age discrimination without even meaning to. It also does in the way that older engineers are less likely to have CS degrees just because CS programs were rarer and less well-known before the 90s.
That's not sour grapes, either. I have a CS degree and worked through math and logic puzzles for fun from the time I was 6, well before I ever knew what a computer was. Interviews like this are practically made for someone like me, but even there, the signal you're getting is I'll gladly do something I like doing anyway, not that I'm going to show similar conscientiousness when it comes time to get into your daily company grind that actually has nothing to do with solving interesting algorithms puzzles.
I'd say it's a signal for a rather mediocre kind of conscientiousness -- that is, for someone willing to put in long hours to achieve a certain goal, for sure -- but for a goal they almost certainly believe to be fundamentally pointless.
And as such, is likely to cause them to develop cynical attitudes about the industry -- and about the companies requiring these tests, in particular.
I thought my ability to build a prototype in a day showed that. Maybe I should have learned every variation of FizzBuzz instead of learning how node works.
