Where not to ornament

Continuing with Quantz goodies I'd like to use him to comment on what to embellish and what not to. We know that the French wrote down many (but not all) of the necessary embelishments and we know the French almost didn't embelish compared to the Italians who could be accused of overdoing it. I assume the Germans did it as well, being inspired by the French and Italians. So instead of asking when do we ornament, the question is when don't we? In chapter 12, paragraph 26, he sais "The majestetic admits few additions, but those that are appropriate must be executed in an elevated style". Perhaps there is nowhere that one shouldn't ornament, but rather how much should one ornament?