Agree w/Hugo - very efficient to subscribe to all in a Folder. We have dozens of these in place.
Default: One user <> One object
More sophisticated: One user <> All of that object Type in a Folder
Still more sophisticated: A group <> All of that object type in a Folder
Not completely intuitive to subscribe using a Folder. Need to select the Folder, then Subscribe, then unselect Folder Type and select the Document or other type, then the event(s).
Helpful to use query builder reports to track existing subscriptions that affect many users / groups / folders. Took a while to figure these out 
