I too, teach in the moment. I call student driven initiatives, gifts, and they are precious. They are springboards into exploration, knowledge, and wisdom, because the kids drive it.
I typically have an outline and intention, but depend on student curiosity to drive what happens, and I steer that in a way so they can productively explore. Sometimes it deviates in a significant, and considerable exploration. But it is always full of music, and humanity.
It requires considerable knowledge and presence on the instructor's part, and is modelled after the same method used by the most brilliant teachers at Juilliard.
The district lawyer presented that these superfluous deviations, like the portion of film I showed when we began sections of Carmina Burana, were irrelevant to music instruction, because they have nothing to do with playing notes etc. The state hearing officer agreed with him. I was left in absolute shock over this. It felt like something out of the Inquisition. I think Colorado neoconism was never more ignorant.