Not enough content for subdivisions.
We're at just about our limit of concurrently running things here. Two free-form RPs with no commitment constraint (Floating Castle and Virtual War) and two storyline driven (First RP and Fallen Kingdom)*, with two more brewing up (Chain Wars and Age of Heroes).
We don't have enough people to even run more content, while certainly there are players not in everything, the main RPers are already on everything and then more. No point to even thinking about sub-sections when the full index fits a single screen.
*For all it is worth, the First RP has a continuous narrative and is closed to new entries. And Fallen Kingdom is just about to start anytime now, also, while being open to new entries at any point, it is pretty story heavy.
"Yami ni madoishi awarena kage yo
Hito o kizutsuke otoshimete,
Tsumi ni oboreshi gō no tama,
Ippen... shinde miru?"