I've been at it intensively for a couple months and my mind simply refuses to cooperate. If anything, after having done 400+ problems I seem to be worse at them than when I started.

Since your time is more valuable than mine, let me summarize:

7+ YoE, MSc. in some science (like it matters)

Last 4 years been mostly ETL with Spark and some backend thrown into the mix with a "senior" title for devops and mentoring noobs.

I used to think this job was a creative one, since writing frameworks and libraries for further use, documenting code and extreme programming made me think that I was building something new and useful.

In fact, due to having extreme ADHD the only thing that kept me distracted during all my overtime was the ability to pursue fun and challenging things. MPP and all the cool stuff you can do with modern tools is fun, interesting and challenging.

Leetcode isn't about fun and challenging things, it's about thinking in one particular way, spitting out solutions using the same exact data structures and jumping through hoops on command without philosophizing or creating anything that can be reused/extended.

This is also what Software Engineering has become: you memorize, regurgitate and participate in agile the masquerade. Creativity is shunned. Tried architectures/patterns are what is expected.

I wish I had practiced law for the past 7ish years instead, because at least all of my skills would still be relevant.