I don’t see how you can minimize “waste of time” lessons without eventually introducing inequality into the student evaluation process. Doing so isn’t worth the trade-off, either. I’d rather a handful of students feel a lesson is wasting their time than have an entire classroom filled with students who are graded using unequal and subjective grading standards… and know it, too.
For you, some homework assignments (and even classtime) were a waste of time because you understood what was being covered. I can understand your view. But try looking at it from the point of view of others. For example, say you felt that the amount of classtime dedicated to Concept A wasn’t enough for you to understand it completely. Naturally, your homework for that night will consist of dozens of problems about Concept A. You’re already dreading it. Then you hear he kid next to you say that he should be excused from the work because, as he claims, he already understands it well. The teacher agrees. Now, how would you feel towards the other student? How would you feel towards the teacher? Pretty darn unhappy, right?
There are bound to be inequalities in a classroom environment. Some students are better at learning. Some get along better with, or are outright favored by the teacher. It happens. But that doesn’t make it right to deliberately introduce another inequality, especially one whose only benefit is to save a student’s time.
Also, if I may say so, it seems to me that this thread is inspired by a complaint of yours-- as I read it, you were (are still?) upset about getting a lower grade, even though you feel you understood the material thoroughly. Even though you did well on tests, you got a lower grade because you didn’t do the classwork. You didn’t do your homework because you felt it was a waste of your time. Hence your question about homework.
I feel compelled to mention that your getting a lower grade was entirely justified. Teachers don’t grade only based on a subjective assessment of a student’s proficiency at the skills they were taught; they also grade according to the (objective) amount of work that was turned in. So while you may have understood concepts clearly and from the start, you did not complete the required amount of homework to reflect that understanding. While your comprehension of the material may have fulfilled the standards of an A grade, your performance didn’t.