A few years ago I was in a hiring loop where four interviewers grilled me on a number of subjects, including algorithms and data structures. They asked me all sorts of trivia questions on assimptotic complexity of this and that algorithm, how to implement this and that, how to traverse stuff, etc. As luck would have it, I was hired. I spent a few years working for that company and not a single time did I ever implemented a data structure at all or wrote any sort of iterator. Not once.
I did spend months writing stuff in an internal wiki.
I can't help but feel that those bullshit leetcode data structures computational complexity trivia are just a convoluted form of ladder-pulling.