I went to school to become an English teacher, but English courses at the collegiate level were intensely frustrating for the reasons you describe: vacuousness,

I went to school to become an English teacher, but English courses at the collegiate level were intensely frustrating for the reasons you describe: vacuousness, self-aggrandizement, and a deliberate shift away from clarity and understandability. Were it in my power, I'd have all students take courses in applied rhetoric. It's amazing how quickly all the bull goes away when everyone is able to see through it. Again, I mostly agree with you, and would be okay with DI, by and large, if it were largely in flow-chart format. The scripts I've seen (non-DI) are screenplays, and the schools that use these assess the teachers on their ability to memorize them. These scripts are blocked out down to 30-second intervals, which is ridiculous. I work in a tutoring center which uses DI (in practice, if not in name), and I've seen great gains come from it. But every so often, it's necessary to break the script due to a larger issue at hand, one that the standardized diagnostic quizzes don't catch. As an example, I had a student break down and start crying because she didn't understand how to multiply polynomials (and was in danger of failing her math course). After consoling her, we went all the way back to multiplying multi-digit numbers together, at which point I showed her how the multiplication algorithm works in expanded form (e.g. 123 * 256 = (100 + 20 + 3) * (200 + 50 + 6)), at which point she was able to see the parallel, and very quickly figured out multiplication of polynomials. All the diagnostic quiz tested, though, was whether or not she could multiply, not whether or not she understood the algorithm. You could point to this and say "That's a failure of the diagnostic quiz", but I think it's probably more indicative of the impossibility of standards (whatever they may be) being completely and totally comprehensive and complete.