Turpissime, I know post and ante can be used as adverbs, but I was talking only about the prepositions ante and post.
I've never seen wheelock's Latin but I believe it doesn't teach ablative "measure of difference" in chapter 7 since not even M&F in unit seven teaches it.
plus, "After bad times" is obviously to be translated with post+abl, and as you correctly said, "three days is a measure, but bad times probably isn't".
I think you're complicating this thread. Rhuiden thought prepositions only took the ablative and all I said is that some prepositions (like ante and post) only take the accussative, and your "not quite" to that inference would only fit if I had talked about the in preposition, for instance, since it can take an ablative or an accusative.
again, i wasn't talking about adverbs, just prepositions, and the post and ante prepositions indeed only take the accusative.
I answered based on the chapter he is in, which made me believe he is a beginner. why would I want to complicate my answer unnecessarily?