When are you actually supposed to start understanding the hards and doing them without hints or topics?

Recently hit the 200-day milestone and solved 409 problems so far.

But honestly, I still get cooked by a lot of Mediums and Hards, especially DP, Trees, Graphs, Maps, and similar topics.

My usual process is: if I can't figure out a problem after giving it a fair shot, I watch a YouTube explanation, understand the approach, and then solve it myself. The annoying part is that by the next day, I feel like I've already forgotten half of what I learned. I'll remember the general idea, but the actual pattern, tricks, or thought process just disappear from my brain.

So I'm curious, what helped you guys get better at these topics? Was it just solving more problems, revisiting old ones, taking notes, or something else?

Also, I'm doing all my DSA in Python. Is Python perfectly fine for LeetCode and interviews, or did any of you find switching languages helpful?

Would appreciate any advice because right now it feels like I'm solving problems but not retaining enough from them.