NPC attack/alert range/radius?

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One thing I've always hated about Fallout is that NPCs, despite being spread throughout a level, all come running into the first room you attack from, meaning all of the combat happens in a rush of mayhem in one space, and when it's done, the rest of the level is empty to explore.

I'd rather alerted enemies stay in their rooms and wait for me to come get them, but for them to take defensive positions and be ready for me if they're close enough to have heard gunfire.

It's possible the AI of the fallout games is simply incapable of this, but is there at least some way to reduce the alert range of NPCs so that only enemies within a certain radius come running when they hear combat happening?