Being a utility-like app (i.e. not an app I’ll often have frontmost, but will instead use via ancillary UI or shortcuts) which is nevertheless in the app switcher all the time (this is nigh-guaranteed to break the Threshold).
I can't believe how much the above bothers me and will lead to my uninstalling the application almost immediately if another solution cannot be hashed out. This entire article is worth a read, chances are that if you are some type of designer it'll describe your behaviour almost exactly.
(via Nik Fletcher)