[rushyrulz]

There are objective factors that count toward a song's difficulty consideration, and I'd say that this list is ordered by heaviest impact to lightest:

*The difficulty of the most challenging pattern or section
*The location in the song of the most challenging pattern or section
*BPM and note density (average NPS)
*Song length
*Patterning (see: Beyond the Universe, Thunder Light, Starlight [Macgravel])
*Stamina considerations
*Hand bias
*Flow

It's hard for an algorithm to accurately weigh all these factors and come up with a satisfactory difficulty rating every time. This is why we do it manually for now.