It is pretty popular for this feature to be turned on at major forums where they have several thousands of daily active members and hundreds of people posting.
I'm talking about.. imagine 5000+ registered AD members and say 900 AD members posting a day. That is where this feature helps.. big big time. But there I just prefer to leave it so that the thread is subscribed and with a checkmark, with no email notification. It is a hassle to clean them up though.
