It is amazing the difference in effort you will get from worksheet to worksheet. Granted the amount of effort may vary immensely from year to year depending on the group of students you have.
Point is, whatever it takes to get students actively involved with the reviewing process where they are not bored and effectively reviewing grade level material in order to prepare them for state or quarterly assessments.
For many middle-school children, math is a real challenge. It is at this age that the concepts begin to get more abstract, and work goes beyond "concrete" ideas like adding and subtracting. It's no surprise that at this age, math can become something the student avoids, or begins to dislike.
These students have weak immediacy. This means that compared to other students, they are slow to come up with the right answers to basic math problems like 6 x 8, or 35 divided by 7. While other kids have the answer stored in their memory, these kids do not. This causes big problems when they try to work through the more complex problems they encounter in junior high math.