That's a good one. I've certainly heard how at least one major character should change by the end - usually the protagonist, except maybe in the case of a story like Gatsby where Gatsby dies because he doesn't learn/change, and it's the narrator who grows in the end. Someone's gotta grow, that's the bottom line.

A change each scene is ambitious - but as you say, it doesn't have to be huge. Even a character entertaining a thought he wouldn't have harbored at the top of the page is change. Forward motion.