I think it is possible to be too efficient but a movie full of details or scenes only interesting within themselves would be a bit tedious. It would be like reading a novel full of parentheticals and footnotes which might be interesting but not move the story forward.
In my own writing I do have a tendency to make the same point over and over again. Mostly because I find my various formulations clever or I feel that they express some extra nuance (when they usually don't). And I think that's where the problem of inefficiency lies. A scene that is clever, emotional, or well done should exist for the purpose of the story you're trying to tell...not just to show off how clever, emotional, or well done it is / you are.
I've seen movies that are too efficient where you can practically see the cinematic strings being pulled and the film moves from scene to scene because that's where it has to go and characters express certain feelings because that's what they have to feel.
In Star Wars there were inefficient parts, like being stuck in the garbage compactor...with Luke being pulled under a second time for absolutely no reason. That has annoyed me for as long as I can remember. I was also still worried about all the Imperials chasing them as they were stuck in that room. Still, the scene served to pace the movie and interject some humor in the middle of a chase. I just wish he hadn't fallen in the second time.
In terms of efficiency for the PT, it would have simply made for a better movie if the romance of Anakin/Padme weren't stand-alone scenes. That was grossly inefficient and ultimately unbelievable. Han and Leia didn't need to run off to a big grassy field or retreat to a bedroom to move their romance forward - it happened in corridors, with glances, with a stolen moment in the middle of action.
I think in most instances, inefficiency is really just unnecessary and a sign of sloppy writing. I think it is possible to tell a story without sacrificing anything while being efficient. And with the format of a movie, time is an issue. In the example you give it sounded like the time constraint determined that something had to be cut, not just the fact that the scene was inefficient. But if the director truly wanted to keep that scene he would have had to cut something else apparently more crucial to the story.
The first scene in Groundhog Day (my favorite non-SW movie) bothers me. It is totally unnecessary. That is a place where I wouldn't mind seeing efficiency work to eliminate a scene.