I like to see what is happening at all the RJs. I like the subforums. (Anyone who has follow this thread the knows this.) I find it is easier to follow with them. Some days I only have time to check out a few RJs. It makes it easier to just look at the ones that interest me the most (both the ones I like and the dumpster fires).
Other days, when I have time to spend, I go through all the RJ subforums and the general uncategoried group. One thing that I am doing to make life easier when I am pretty well caught up is to look at the day/time of the last post. Some airlines may go 2 or 3 days without a post, and then a rash of postings. Others seem to get a dozen every day.
Regarding the perception of fewer postings, you can run metrics. My guess is breaking them into subforums gives an impression of fewer postings, without really much of a change. After all, you look at a subforums with just a couple of unread threads vs. a general uncategoried group with 20 unread threads and it is easy to get the feeling you are looking at fewer posts.
I have seen a diminishing of the number of postings on American, without any changes to it as a subforums. I attribute this to the Seniority List Integration being a done deal, flow and OTS hiring starting in earnest (after all the Letter T furloughs got called back), and AAG getting pay matching Delta and United. Fewer controversies, fewer posts. They need to drag a passenger off the plane to stir more posts. NOT. (I don't wish that on anyone!)