I have a theory, based soley on my gut feeling and nothing that could be considered even remotely scientific, that if I practiced nothing but kotegaeshi for a year my ikkyo, nikyo, sankyo, etc would all get better (assuming of course I already have some level of base profiency in the technique).
I base this on my understanding that most of what makes the technique work is proper timing, distance, positioning and what-have-you. All things that are learned and practiced in every technique albeit with slight variations.
Mostly I'm blabbering and fully expect to roasted by the more logical types here
Bronson