By Daniel T. Parker
I had a graduate school professor who taught "Teaching College Writing", among other (non-TESOL) courses.
He continually reminded us about the "affective triangle", i.e., the classroom chemistry formed by the mixture of teacher, students, and materials/methodology. His usual point was to remind us not to put too much faith and/or dependence upon a particular textbook... but basically he was saying that the same methods won't work for different teachers, and different classrooms will have different reactions to the same methods and/or the same teacher. The "disciplinarian" will be effective in some classes, the "mother" in others, the "sarge" in others...
It's frustrating. But I can't argue with his conclusions. And I would say, maybe I'm going out on a dangerous limb, but I would say that ANY teacher who says the same text and the same approach works for every class just isn't paying attention.
He was the first professor I ever heard who scoffed at degrees. He said we needed the documents ("gotta know the secret handshake") for employment reasons, but he saw teaching as an art, and would say that giving a guy a few art classes and putting a brush in his hand won't turn him into Picasso.
He wouldn't advise us to ignore cultural differences, or be careless about methods & materials, or refuse to listen to other teachers... but he would, and did, point out that every classroom we step into, every single day, is a laboratory, and we're not the cheese or the rats... we're the maze.