When working in class with these grammar shows, we've found that they serve their main purpose: to give the student the full picture. They are a great tool for revising.
I don't know about you, but I never seem to have enough class time for reviewing former syllabus. But with these I can do it in a few minutes, and the students don't get that bored, glassy look I've seen all too often when going over past materials.
They actually ask for repetition. Also, when the need to revise arises - before a test, or at the end of term - you cannot be certain they are doing it properly. But it may be done in the class or lab under your supervision. That's much better.