If conscientiousness is what companies are going for, I think they're still interviewing wrong.
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 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.
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.
And as such, is likely to cause them to develop cynical attitudes about the industry -- and about the companies requiring these tests, in particular.