Practice, Practice, Practice?

I feel that too much emphasis has been placed on practice exercises rather than theory. When I say practical exercises, I do not mean practical sessions, but homework and past-year tests. If this were a subject such as mathematics, I would not question this method, but for science, it is my opinion that a lot is based on knowing your facts. Of course, for most subjects, some amount of practice is still needed on top of the theory aspect of learning. However, I believe that for science, this amount should be kept to a minimum. Unlike mathematics, for science there is no significant gain for the same amount of practice. As such, I feel that the valuable class time that is spent on going thorough worksheets is better spent going through important facts that have to be deeply ingrained in the minds of students.