The drawback sending out emails all with the same subject is that the receiver is having a hard time setting them apart.
Especially in the work or medical realm this makes people miss crucial information.
Worse are organisations broadcasting on Twitter, but not responding at all to improvement suggestions. [Wayback/Archive] @ZorgDomein / Twitter gets both wrong (and is also unusually hard to find phone contact information for on their web-site):
The Wiert Corner - irregular stream of stuff 