Jay, that your situation may be that you never improve a product after its release, if so let it be. I have yet to make anything where added features were not requested at some time after the release. Coming back to something you made years ago to add a feature you are up the proverbial creek, if your code is not maintainable. I always argue against any documentation outside the source, such is never maintained, but explaining what the heck you are doing in a comment does make life easier for whoever (usually yourself) that has to update or fix the code five years later.
Happy new year,
Erik Malund