"Clubs in Japanese schools actually chose set in days for their activity, they didn't simply rock up to the hall or room whenever they pleased for club activities, though if they did, it'd usually be equipment related."
This is actually true. I can confirm. I joined clubs in the University, and they do have set in days for club activities, they don't just do it whenever they please. Some clubs like a literary club or anime/manga club that double as a library will be open pretty much most of the week, but that'll be just for free use or if you need to get something/restock something/store something, there'll be no actual activities outside the days they've set up.