Question What is the smallest proof of concept that proves a short is shootable?

[Miranda_]

I’m developing a visually ambitious dystopian short for a small team. Before committing to the full approach, what would you test first: one difficult shot, a complete dialogue scene, the main location, or a short sequence combining image, sound and editing?

I’m looking for the smallest test that exposes weaknesses—not just one attractive frame. What did your proof of concept reveal that storyboards or planning did not?