I unscribe when the thread dies out, or gets boring (overly repetitive), or annoying (to stop myself from saying what I really think...
).
I have some threads that I always stay subscribed to, becauses of the great advice on them & they are really informative. Some topics are things, I've not encountered yet, or don't currently have a problem in that area, but who knows...ZoE is only 2...and I want the knowledge at the ready should I need it in the future.