Hi, Jana.

There is not a specific time that a student must reach to determine mastery. Each child works at his/her own speed. I have a son who will NEVER get problems done at the suggested speeds because he has some mental processing delays! However, if your son knows the facts 'inside and out', you can ease up on the drills/practice sheets. However, I would not recommend that you do away with them altogether. Just as with anything, if you don't use it, you can lose it.

Hope this has helped. If not, feel free to contact RightStart's help line at (888)272-3291 or email them at info@alabacus.com.