Every scene has a value in play — safety, trust, hope, status, freedom — and a functioning scene moves it, usually from positive to negative or the reverse. Write the value at the top of the scene with a plus or a minus, write it again at the bottom, and if the two are identical the scene is information delivery wearing a scene’s clothes.
It is a better test than "is it interesting" because it is answerable by somebody who did not write the piece. Notes given in these terms are actionable in a way that "it drags" never is: you can point at scene four, show that trust starts negative and ends negative, and the conversation moves to what should have changed.
The shift does not have to be large. A scene where trust moves from slightly negative to badly negative is working. A scene where it starts and ends in exactly the same place, however well shot, is not.
What is a value shift in a scene?
The change in what a value — trust, safety, hope, status — is worth between the start and the end of the scene. A scene where the value does not move is delivering information rather than dramatising anything.
How do you test a scene for a value shift?
Name the value in play and mark it positive or negative at the top and at the bottom of the scene. Identical marks mean the scene is not working, regardless of how good the dialogue is.