I doubt that his powers adapt themselves. I personally think that it s the user's decision that matters how much power exactly to use. He can be as strong as he wants to be, yes, but that doesn't mean that he is able to keep this power level for long. Why do you consider it irrelevant? I don't mean to criticize, but it is no better than assuming the entire issue irrelevant because the entire Justice League was used as the means of showing the power of the foe Batman was facing.