I had different multireddits. They were each basically used for different moods. I had one called "humansbeinghuman" when I wanted to watch some slapstick, dangerous stunts, or fights. I had another called "goodbodygoodmind" which had stuff in it that I thought would help me be a better person, like a weight loss sub, a sub for decluttering and minimizing possessions, and a bunch of creative hobbies I enjoy like worldbuilding and game development. I also subscribed to a community-created multireddit called "safe for work porn" which was all the beautiful images of nature, landscapes, food, architecture, and other cool stuff.
But I also tried to make sure that when I made a multireddit, I only combined subreddits with similar activity levels, so the multi filled out evenly and one sub wasn't dominating the content of the multi and burying everything else. I mentioned this problem about Hubski recently:
and I think a multireddit-like solution (grouped feeds) will help alleviate that problem. On Hubski, I'd have one feed that's entirely music tags, while another would be my main feed with all the other stuff. (Though I might later subdivide further if it became necessary). With only one feed, a single big tag like #music can really make the single feed go boom.