I wonder about that sometimes. I would argue that, unless you have perfect cadence (not me), you do more work with every pedal stroke with more mass. And every time you accelerate from a stop or increase your velocity, you do more work with more mass.

It's basic physics, but I don't know if it matters much in the real world with most cyclists. It's just one of those things I think about on long days. Like on my last trip when I reduced my load and the cycling got much better, even on calm flat days like on the Erie Canal. Maybe everyone has a better cadence than I do.