Hello Codeforces!

From time to time I find myself unable to solve or taking too long to solve some B/C problems from div 2. Almost all the time when I read some red's comments after contest they describe those problems as "standard" or "classic" or "straightforward implementation", at the same time that I've never seen a similar problem before.

From what I've seen, everyone recommends solving random problems slightly above your comfort zone in order to get better. I've been doing this in codeforces for a while, but I feel like I never came across those "classic" problems while practicing in codeforces (I think that's because problem setters need to "obfuscate" the statement in those standard problems).

So my question is: Is there a better way to practice those "classic" problems (maybe other platform)? Or is just keep solving random problems a better idea?