4 key only
SR is broken for sure, but I feel like it’s sometimes exaggerated. A lot of 3* can be harder than 5*, and sometimes even ranked maps. I’ve played quite a few mania maps and I have a collection of ranked maps which are comparatively harder than other maps, and it’s only around 5-10% of the total.
1* mania takes around 1 week to FC
2* takes around a month maximum to S most charts
3* can take people anywhere from 1-6 months on average to S most charts
4* S on the comparatively easier songs usually from around 3-12 months
5* easy charts S at around 6-24 months
5* hard charts from 12-36 months
and from there on difficulty kind of breaks