It should, of course, be optional - but I have a fairly low-volume sub (or three) that I babysit.
I think it easiest if I describe it?
I babysit the v/Guitar sub. Sometimes, people will submit questions and they don't get a timely answer 'cause I don't notice them. The same is true with v/Mathemagician.
Because it's low volume, I'd like to be able to get a notice (perhaps a PM message) that tells me that a new submission has been made to a sub that I'm watching.
I think calling it "Watched Subverses" would be a great name and suggests what I'm really hoping to see as a feature. I'd also kind of like a "Watched Thread" system, as well, but that seems like it could result in a lot more server overhead and might be wasteful. The former seems to be much less compute intensive and is probably pretty easy to code.