Recently I have observed that many of the Red coders have a pretty scattered submission heat-map, yet still, their ratings have increased significantly in the past few months. Is there some other platform that is equally or more preferable for practicing than codeforces? especially for high ratings?

Also, the highest I have reached on CF is Candidate Master(not really a high rating), which was just by randomly solving as much of codeforces' problems as I could, but that technique seemed to stop working with time. Now, I have got time again and I want to start CP aggressively again! Any tips on how should I focus on practicing to become better at CP from now on would be welcomed.

Thanks ^.^