But these imperatives are inconsistent with one another, because students tend to be quite conservative in such matters; and the more academically successful they are, the more they will demand the familiar and become agitated by anything unfamiliar and therefore unpredictable. It is possible for a good teacher to manage this agitation, but it's not easy, and it requires you to have the courage of your convictions.
You get this courage, I think, by being willing to persist in choices that make students uncomfortable. Now, some student discomfort results from pedagogical errors, but some of it is quite salutary; the problem is that you can't usually tell the one from the other until the semester is over — and sometimes not even then. I have made more than my share of boneheaded mistakes in my teaching, but often, over the years, I have had students tell me, "I hated reading that book, but now that I look back on it I'm really glad that you made us read it." Or, "That assignment terrified me because I had never done anything like it, but it turned out to be one of the best things I ever wrote." But if I had been faced to confront, and respond to, and alter my syllabus in light of, in-term opposition to my assignments, I don't know how many of them I would have persisted in. It would have been difficult, that's for sure.
The belief that constant feedback in the midst of an intellectual project is always, or even usually, good neglects one of the central truths of the life of the mind: that the owl of Minerva flies only, or at least usually, at night.