I'm not following how the single-shot modus operandi seems to contradict the terrorist theory. To my line of thinking, the cold efficiency would be purposefully employed to heighten the sense of terror in the community. Being able to kill from a decent range without wasting a lot of ammo is by design a terror inducing concept. That's why military snipers are so effective. Not only do they take out people, but they do it behind enemy lines and follow up by escaping and evading, only to strike again.
Can you explain your opinion to me (I'm not trying to pick a fight, but rather would like to understand your viewpoint)?
I just don't see how taking a single shot creates more terror. I think people would be just as terrified, if not more so, if the shooter was taking several shots, especially if the murderer was firing on wounded victims.