Is it better to have many narrow categories or a few broad ones?

I was literally rearranging my forum categories because the whole place was looking so rough. There are too many sections everywhere and half of them are empty. I think few broad categories make more sense especially when the community is still very small. One forum i joined recently had like 40 categories but activity was weak.

It makes it look busier if you have less categories. But then if those categories are too vague, what interest would members have when they can find the same ones on all the other forums?

I have a forum that has way too many subforums that I need to clean up lol. I think if you keep it simple and have around 7 subforums you should be fine coming up with content to populate each sub forum. I think having too many can be overwhelming, especially for someone new to forums.

Initially, don't over categorise.

Start with a few broad categories and gradually add sub-forums as and when you see specific topic being discussed heavily.