FWIW - CTY takes a very different approach than what is described as the Kumon method in these posts (we've never tried it ourselves). It moves very quickly along and only if your child struggles in an area is s/he given more work to do to learn the skill - it is not mind-numbing or repetitive. If you are looking for enrichment, I would strongly encourage you to try CTY.
My kids have done both Kumon and CTY. Both strategies emphasize different mathematical skill sets. First kid finished CTY K through Algebra in elementary school (3 to 4 months per grade level). So, it's also fun but moves quite fast if you work 1/2 hour a day. There is more geometry and probability than Kumon. Kumon, on the other hand, has very little geometry (none) according to DS but is very extensive in Algebra 1, 2, and Trigonometry (particularly regarding the variety of ways/tricks to factor and treat polynomials). In elementary school DS says he could factor "a ham sandwich" and Algebra was far more extensive than CTY or EPGY Algebra. in fact, the Kumon experience made him blow through CTY on the computer. Art of Problem Solving Algebra (1, 2, and 3) is by far the deepest and most rigorous treatment with requirements for proofs when completing the problem sets every 3 weeks. This group has now introduced a preAlgebra series rigorous but popular (nationally) that had not hit the production lines when DS was in the early elementary years.
I would also recommend CTY if your child likes mathematics. EPGY is the cheaper version -- same software but no tutor and an electronic transcript of performance (CTY outsources to EPGY - Stanford). For those that are not trust fund babies math via EPGY is cheaper (EPGY open enrollment -- even cheaper).