How do people manage to solve over 5 problems per day?

To me, it takes 1-2 hours at least for a new problem that I haven't encountered. This involves attempting to solve it on my own (In most cases I don't), then looking up the optimal answer and understanding it, understanding edge cases (in most cases I have questions and I ask an LLM), and sometimes looking up most commonly asked follow-ups and variants. This takes time, and after all of this, I end up getting mentally tired after 2 problems, yet I see people doing 100 problems in 2 weeks here, how? Am I slow?

And don't get me started on revision, I forget the edge cases when I don't revise problems regularly, so that also takes up time.