Mania leaderboards should be seperated between 4K-5K-6K-etc. And here's why, first of all you need to know that score+difficulty determines the amount of PP you get. More dense note patterns add more general difficulty but don't necessarily mean they're hard patterns. Because 7K has more lines then 4K a beatmap is garantueed to be more dense. This makes it easier for higher K players to grind pp and become higher on leadeboards then 4K players. I'm saying they should be seperated but for all i care just make them a second leaderboard or something. I know you can give the argument to just learn 7K and that's a fair point but i don't think it's totally necassary to learn 7K to be high on leaderboards, it's just to get higher on the leaderboards faster but having a seperate leaderboard between all K players would be a nice touch.