Again, if I have scripts to work directly in the player since the beginning I prefer to test without save. But like I said many times, I do what I think its best for me, not trying to change minds or anything.
I'm trying to get you to see that what you're doing is not representative of an actual use case; what you're doing is something the user will never, ever do. And your methodology is not something that needs to be propagated to other scriptwriters. I'm worried less about you and more about anyone else reading this. And strictly speaking, what you think, and what is right, are logically unrelated terms.
And it's not like the cost of using a clean save game is that high. You hit the continue button. What you're putting forth is that scripts have an innate propensity to break when performing the act of loading a save game that has never seen the script in question, which doesn't make sense. If that were true, all of Skyrim would be broken.
Either way, I'm done arguing the point. You either accept, fundamentally, that what you're doing is not an actual use case (forget about the technicalities of the game, save game architecture, script behavior, so on), or you do not. And if you're fine testing your content with invalid use cases, that's your prerogative.
Edit: I would also say that there is nothing wrong with using a COC from menu method to do prototyping or very early testing. My primary point is that that test case should not be the final indicator of the functionality of the script; it has to be tested with a real use case. The more, the better.