In this answer there is a reference to a Kaddish that is better left unsaid as it is a Kaddish L'vatola.
Kaddish does not seem to have anything in it which cannot be said in a vacuum. Is there any reason to not say Kaddish other than the possibility that it doesn't accomplish anything and would be a possible waste of time?
I am not asking about whether Amen should be responded to such a Kaddish. I am asking if there would be any reason for the Kaddish itself to not be said. This could be relevant for a chazzan to practice singing Kaddish, or just to sing Kaddish to myself because I like the tune.