The more experience I have the harder they are for me to solve, as engineering problems tend to have very different mental models to reach the solution.
First thing you do is you ask people is that the problem they are actually need solving - most of the time refining the problem leads to there being something totally different that is requires. A process of asking people “why you want this hard to implement thing” and discovering that what they actually need is something smaller and more aligned with whats currently working. Leet code is the opposite usually - you see a simple problem but “there is a twist” that would be considered scope creep generally.
Then the implementation of the solution itself requires knowledge in your head, whereas years of experience has led me to put a lot of that knowledge out of my head and into “places I trust to find the answer” - google stack overflow, HN etc. And keep in my brain only the general abstractions of how to apply them. This allows for vastly more powerful solution making as you can stand on the shoulders of giants.
Example - see you have a leetcode puzzle. My first instinct is to use my google fu to find out what the best current solution is out there, understand it and either apply it or modify it a bit if it needs tweaking.
But that would be considered “cheating”. Leetcode: 1, Life skills: 0.
And there is the damn time pressure. Every time I’m pressed for time on my day job, its a signal something in tech or management has gone wrong, and I seek to optimize and fix that. Rushed engineers make poor, shortsighted decisions.
Each time I do an interview I feel out of sorts as all my instincts scream “something is really bad, you should _not_ be doing this solution this way it will bring pain in the future” But you have to power through. And I probably look way less impressive than someone who has the solution memorized.