I have my kindy son do one page every day from the Middle Curriculum Phonics book and one page from Singapore Math. It doesn't take alot of time. I also have him do 10 sight words and 10 spelling words each week that I show him and have him write out. He likes doing IXL math on the computer and he reads 20 minutes a day.
Kumon seems like such a snoozer and killer of creativity in children. I haven't had the heart to force my kids to do that.