Educational Models for "One Size Fits All"

I don't think a "one size fits all" model is realistic or effective

I agree with this. Do you think most classes are designed with a "one size fits all" mindset? If so, how?

If one was doing radically different types of Instructional Design work. For example, I deem that it would be best to avert the Traditional Instructional Systems Design approach and instead consider using a Constructivist or Critical theory/critical pedagogy to achieve the desired objectives.

Please explain this further.