We are using Saxon and are not supplementing. I do add math games because dd loves games. I've considered supplementing, but have realized that it's just too much, at least for now. We school 3 to 4 days a week and between phonics, spelling, reading, Bible, math, science, handwriting, outdoor time, etc. there is just not enough time to throw in another thing for us to do, so for now we are good. :D
HTH!