I believe that last-mile edits do not significantly improve the quality of (most) creative work. To produce high-quality work, one must have already "cached" their "motor heuristics," which, in simpler terms, means having dedicated thousands of hours to deep and deliberate practice in their field.

The definition of 'last-mile edits' is very subjective, though. If you're dealing with open systems, it's almost unthinkable to design something and not need to iterate on it until the desired outcome is achieved. In other domains, for example, playing an instrument, your skills need to have been honed previously: there's nothing that will make you sound better (without resorting to editing it electronically).