Maybe this would be a good place to elaborate on this. (So I can refer to it.)

The idea is that if you ask something like the main chatroom, it will often go unnoticed among the amount of chitchat that is going on there.

Posting it in chatroom devoted to specific subject could help reach the people interested in that subject. (If they visit that room occasionally.)

Even posting a pointer to a discussion which is going on in the main chat room could be useful - so that in the subject-specific room we have links which might be interesting to room visitors.

I have to admit that it does not go very well.

Some of the rooms were started by someone else and I am simply keeping them alive.

But for example Set theory room used to be active. So used to be Commutative algebra room.

It seems that rooms related to some of site-maintenance issues are more successful.