There's also perhaps something to be made of whether or not the antagonist/s make the group of protagonist pull together, or drive a wedge and break them apart. Hill have eyes, and Death proof pull the characters together, where as in The Thing, Alien, The Exorcist, it pushes them apart until the third act where they start working together again, Or in "Night of the living Dead's" case brings people together then breaks them apart. Each equation comes with its own different type of tension.