osu!mania Ranking Criteria wrote:
Each key mode in a beatmap set requires its own spread. For example, a 4 key beatmap would require its own Normal/Hard/Insane in order to create a proper spread, independent of any other key modes present in the beatmap set.
With a probably recent change to the RC, this rule is already covered by other rules in the RC for all modes. In its current form, this rule is rendered redundant the following entry:
Beatmapset Ranking Criteria wrote:
All game modes within a beatmapset must form a spread starting from the lowest difficulty level dictated by the song's drain time. For difficulties above the lowest required difficulty level, the spread cannot skip any difficulty levels and there cannot be any drastically large difficulty gaps between any two difficulties.
A note above the rules of general RC makes it more clear:
Beatmapset Ranking Criteria wrote:
Note: Each of osu!mania's key counts are considered individual game modes throughout this section.
Since each of the key counts of mania are considered individual game modes, the entry from general RC already implies that each key mode requires their own spread. Therefore, the mania RC rule is redundant, and can be removed.