For Math, students who get 4/5 of the most difficult questions correct on the homework will either get different Math homework or none for that day. I love it. I can't say how many days I struggled with forcing DS8 to take his time to make the Math neat, when he just wanted to whip through it because it took no thought.
That "most difficult first" strategy is really a great one for avoiding repetitious, unnecessary work. Keep in mind though that in Weinbrenner's book this strategy is:
a) supposed to be short term (if a student is continually able to do this, the teacher is supposed to plan and deliver alternative/more challenging instruction)
and
b) supposed to "buy time" for other learning.
You might consider working with the teacher to come up with an alternative homework kit that focuses on a math topic/activity that interests and engages your child. When your kiddo buys his way out of the regular homework, he could perhaps pull an assignment that would take a comparable amount of time from the kit and work on that instead. Others might have some ideas of resources that would be good for this. The idea is not to provide busy work, but to allow your child the same opportunity to learn time management and study skills that he would have if the homework were appropriate.
FWIW, I think that there is a lot of value in Weinbrenner, but don't be surprised if initial implementation is a little bit spotty. It isn't as easy as she makes it sounds
