[Johnny1A.2]

Another consideration that's been touched on upthread, but needs a larger look, is that groups, families, organizations, tribes, etc that follow something along the lines of this code often, maybe I should say usually, have some kind of mechanisms in place to limit the ability of individuals, esp. junior-ranking individuals, to get the group into wasteful, destructive vendettas.

The nature of those mechanisms can vary widely. For ex, there may be strict rules of behavior to keep the members of Group A from coming into direct contact with Group B except under controlled circumstances. If Billy Bob Corleone is under strict orders to Stay Out of the Hatfield's territory, and he follows those orders, the chances of a nasty encounter (and ensuing vendettas) with the House of Hatfield decrease.

(In this situation, Joe Hatfield is probably under similar orders from Old Man Hatfield.)

Alternatively, there might be unwritten rules about when the organization is obligated to back up the individual, and when it's free to throw him to the dogs without losing any 'face'. In that case, Patrov Harkonnen is free to mix it up with Janos Atreides, but since he did it without the blessing of the Baron, he's on his own with the Atreides when they come for him.

There are lots of ways it can work, but there are usually some kind of limits to keep it from blowing up on a daily basis.