I use a catch-all for memes that look cool that I copy from meme communities, however two of my PSL partners created a brand new musebox each for the threads we had going, and we use them to do world building and dropping things like visualocities and IC interview/quiz answers in addition for creating new threads.

So if you prefer to use a catch-all community, go for it, but some people find it neater to create a community just for one concept that has the likelihood of ongoing threads.