I don't want to be disagreeable..... but count me as a negative for subforums all around
The only time I ever see anything about subforums is when I'm trying to start a new thread..... and in that case, the more subforum choices there are, the harder it is to figure out where to put it... and I think like most folks, I have a limited amount of patience for figuring that out, so the thread will most often default to whatever seems to be the "general" category when there are too many choices on a forum.
The more choices of subforums, the greater than chances of something being mis-filed.
otherwise, when I'm logging in to read, I look at new unread posts since my last visit
and if a topic is interesting I open it if not I don't. I pay zero attention to what subform it's in
and if I'm searching for something, I'll be searching keywords.... again, subforum is of zero help.
Instead, I support the idea of encouraging good thread titles.