Bingo,

I still disagree. I have seen several movies either based on real events where everyone knows who dies or fictional events where they straight up tell you who dies at the beginning and yet I'm still surprised at the end when it actually happens.

or heck

even movies I HAVE SEEN BEFORE and still find tense scenes to be tense, even if I know how they end.

This argument sort of says that any scene in the middle of a film can't be tense because you're relatively guaranteed no heavies will die at least until the end of the film.

And it says that as soon as a movie has a sequel, that the original can no longer have any tension.

Does Raiders have no tension, now that they've made Last Crusade?

Is Wrath of Kahn no good since they've made... all of the rest of them?

Does the duel at the end of ESB not have any tension now that Return of the Jedi is out there?