In my opinion, I believe that the foundation and mastering basic arithmetic is the most important quality needed for any mathmatics program. Without this basic foundation and, more important still, the understanding of the principles; any student will struggle with numbers.
I disagree with a number of teachers and parents who do not take seriously practicing not only the new concepts as well as the old ones. As wonderful as Saxon is, they suggest just doing half of the problems. Why? I know most parents and students bulk at the idea of so much homework. The problem with that idea is that the student won't master the basics as well. In reality, the more practice a student has had, the faster they can actually do the homework. Just like Candra's dance teacher once told her, "Practice until you can do the steps in your sleep. Then when nerves or other problems present themselves, the steps become automatic and the harder exercises become easier." Both of my children had more that 50 problems each and every night. Now that they are grown, they enjoy seeing how hard of a problem they can do in their head.
Adding games and other exercises can only help. They can be fun also. There are so many things out there now, that you can make sure the children like them and have plenty of choices.