Do you have any of your forums set to notify you by email when a new post is made? What sections do you use it for? Right now I'm usually only using it for the Introductions forum, and on one site I have it turned on for the Action Alerts forum as well. (That's where people post notices about calling elected officials on an issue.)
The only forums I am subscribed to anywhere are the Article Submissions forum here and the Announcements forum on vBulletin.com.
I tend to avoid subscriptions entirely. Seeing as I'd rather log in and check for myself, I don't really see the need to receive e-mail updates each and every time something new is posted - it can get a bit frustrating.
Do you find it hard to go through and find everything? On a busy forum, it may be hard to keep up with certain threads that you want to catch up on. And then there's the factor of forgetting. Without thread subscriptions, I would be so lost and forget about half of the threads I create and questions I ask. :lol:
With certain forums, it may be worth it to subscribe to the entire forum if you really want the information delivered regularly; I subscribe to the vbulletin.org Add-On forums for 3.8 and 3.7 because I like knowing what new mods were posted that day.
I don't use it at all to be honest I am on my site often enough to find out the information - It was set up here at AdminAddict by default when I first signed up and I received like 100 emails in one day and it annoyed me so i came in and changed it all.