I must say though that I don't think the opening monologue reveals too much. It reveals something but the city still feels weird, you don't truly understand the strangers' goals at the beginning, and there are still plot twists. If you don't even know about the strangers at the beginning, I wonder how the movie would play... a pity I cannot wipe my own memories and re-experience it ;)
This happened accidentally with Memento [0], it it became an incredible film. Without all that setup in the first scene, you exist with the protagonist as he discovers his world.
I've tried it with other films and they give away too much information, you the viewer are practically handed the whole script.
Give it a shot, you might like doing it that way.
"The Wadsworth Constant is the idea (and 2011 meme) that one can safely skip past the first 30 percent of any YouTube video without missing any important content."
I don't quite think the UI_at_80x24 constant has the same ring to it.
Part of the tension is knowing Leonard is going to kill Teddy, we just don’t know why.
Skipping the first 10 minutes is like skipping the last 10, "I just know where this is going anyway". Nope. So much can happen in 10 minutes! Plus, you know, they filmed that part for a reason.
It's also like skipping the first chapter of a book: sure, some books would be improved by trimming their clumsy beginnings, but good books aren't.
In general, I disagree with your rule of thumb. My favorite movies have cool beginnings, and it'd be a shame to miss them.
The first scene really drew me in to wondering WTF is this movie going to be about?!
The first scene created the mystery. One of my favourite movie openings.