Are Teachings developed "after the fact"?

This might be a poor question, for which I apologize but I am trying to gain some insight on this idea I have had for a long time... It seems that paths and practices are taught to people with the intent that they have the same results that the teacher did by doing that. But the teacher might have come across the practice by accident, and the teaching is simply their experience, not a principle. When I read suttas, interviews, articles, different sects' explanations and so on, there is an almost infinite variety of statements and interpretations, and people seem to get lost in words. If a practice was really "true" absolutely, then there could be no difference of explanation or understanding, right? It certainly is not like Physics, where everyone would get the same results of a clear experiment. If a Teacher was so wise that they came up with the practice before they had used it, that would be a miracle indeed. Is it not the case that all that is taught about spiritual development is basically experiential? Even the Buddha had to learn by doing. We are just following what he said.