I agree what mo said, it gives a risk of mappers pushing single diff tv size for ranking
However, the main point i want to bring is that the proposal itself is meant to encourage mappers to push full sized song as there's isn't much players play full sized low diffs, which this phenomenon isn't clearly happening when it comes to tv sized maps (at least compared to full size). So it's reasonable enough to remove 2 diff rule for full version songs (>4:15) but not in tv sized maps (mostly referred to 2:30 if counting rhythm game size and anime TV size songs, but it this case, it's referred to songs shorter than 3:30). And removing 2 diff rule is still unfair to full size mappers because mappers can map a tv size calm song (e.g. R3 music box) with only 1 normal or easy diff, rendering they can rank single diff mapsets with (more than) half of the drain/play time then full size mapsets.
So besides what mo has proposed (to prevent abusing this rule by ranking low diff approval while the song is upbeat), i would like to propose the guideline in another way to prevent this happening so tv size mappers should map almost the same drain time as single diff full version maps:
Sorry if it's hard to understand, my English is quite bad and i am not good at explaining things
However, the main point i want to bring is that the proposal itself is meant to encourage mappers to push full sized song as there's isn't much players play full sized low diffs, which this phenomenon isn't clearly happening when it comes to tv sized maps (at least compared to full size). So it's reasonable enough to remove 2 diff rule for full version songs (>4:15) but not in tv sized maps (mostly referred to 2:30 if counting rhythm game size and anime TV size songs, but it this case, it's referred to songs shorter than 3:30). And removing 2 diff rule is still unfair to full size mappers because mappers can map a tv size calm song (e.g. R3 music box) with only 1 normal or easy diff, rendering they can rank single diff mapsets with (more than) half of the drain/play time then full size mapsets.
So besides what mo has proposed (to prevent abusing this rule by ranking low diff approval while the song is upbeat), i would like to propose the guideline in another way to prevent this happening so tv size mappers should map almost the same drain time as single diff full version maps:
While i felt that songs with between 3:30 and 4:15 probably stays on the grey zone, since some "full sized" songs with that size (especially between 3:50 to 4:15, from my experience) and "Hard" isn't exactly lands on either "low diffs" or "higher diffs" but stays on between. So it's hard to desire should we allow a map that sized can be ranked with one diff or not.Ranking Criteria wrote:
If the drain time of a beatmap is...
...lower than 3:30, the lowest difficulty of each included game mode cannot be harder than a Normal and should include 2 or more difficulties, regardless of how the song feels. Because osu!mania does not have a difficulty-specific Ranking Criteria yet, an osu!mania beatmapset's Normal difficulty is defined as a difficulty below 2.00 stars. For hybrid beatmapsets that include osu! difficulties, the additional modes’ lowest difficulties cannot be harder than a Hard.
Sorry if it's hard to understand, my English is quite bad and i am not good at explaining things