You'll find me strange, but I find more enjoyment in a leetcode than in implementing a "hard-CS thing". Probably because it's easier and you're a better engineer than I am.

Note that I would never require leetcode during a job interview. However, a single LC question is a small-sized puzzle I can solve in a day (or a weekend). If I want to write a ray tracer, well... Good bye life for a week or two.

In other words, I have difficulties finding 50+ hours of large chunks of time to be unavailable to my family in my supposed off time. Leetcode I can do on a couch while my SO watches Games of Thrones.