Graded curriculums skip to a new skill every 6 weeks, whether the student is ready or not. All together, it takes them nearly 3 years to learn 12 hand positions on the clock. In Mastering Mathematics, they would be taught how to read a clock, following the prescribed order in the Parent's Manual, until they have mastered it. That is more logical than spreading out a concept for 3 years, when in most cases it can be learned in less than 6 weeks. Top of page 2.
Some children have difficulty handling more than one concept at a time.
Math follows the same principle. They won't get bored with concentrating on a single skill. Instead, they will have confidence when they have mastered it. Top of page 3. To answer this question, I would have to know your child personally.