Why Iblees Was Tested Only Once?
It didn’t say anything about the question being ridiculous. The point is that we have been asked by God and His Messenger SAW to not speculate. Since we don’t know anything about Iblees being tested previously, whatever we say would be purely speculative in nature. Instead, we should defer this kind of questions for the Day of Judgement, and in the meanwhile use our time productively to focus on what we do know with certainty.
So you are saying we don’t know how much and what kind of tests were passed by Iblees before Adam(creation of man), or even don’t know if God had tested him or not. So on the behalf of ”we don’t know properly the things” we cannot get to the point to make an argumental assumption. Got It, Right.