My 6 year old's math problem

The other day, I realized that I had a problem with my 6 year old's math. You see, a year ago, when I ordered a pre-algebra workbook for his brother, he asked for his own workbook. So I got him the first Miquon Math book on the recommendation of a reasonably like minded friend. Collin loves his math workbook because he can flip through and say, "look at everything I've done." The problem is, that I just realized that it's been a year, we're not done with the book (which is supposed to take 6 months) and what is being taught is completely irrelevant to Collin's math knowledge. I couldn't even tell you what the book covers as it seems to touch on a little of everything without ever going too deep. In the meantime, Collin adds 2-3 digit numbers in his head, figures out speed and time while we're in the car. He figures out how much money he'll have left in his allowance account if he buys something. He is forever figuring out how many days until his birthday, Easter, the baby's born, Halloween, his eighth birthday and so on. He probably spends at least 10 minutes a day figuring out how long it will take him to save enough money for some toy, given that he gets $4 every 2 weeks for allowance. And what if he gets a twenty dollar bill for his birthday? He figures out how long it is until some TV show he wants to watch, what time it will be when dinner's ready if dinner is 15 minutes away and it's 6:20 now. He takes money from the coin jar, sorts it, counts it, adds dimes to nickels to pennies to quarters and then tries to convince me to let him keep it. He figures out what year something happened if it happened so many years ago and even has use for the occasional fraction. I really think he devotes a good 30 minutes a day just to figuring out various numerical problems. In the meantime, a couple times a week I hand him a workbook which is having him use "greater than" or "less than" signs to indicate which number is bigger for 6 pages. Why am I wasting my kid's time like this? I think I'm going to leave the darn book in a corner somewhere. If he really wants it, he can get it, but I'm not pulling it out again. While I know he enjoys having a workbook, I think that next time he asks about his math, I'll just offer to teach him something new without it. Now I remember why I never wanted to bother with a math curriculum with my oldest son. With him, we just sat down anywhere from 1 to 3 times a week, learned to do various math functions and moved on once he got it. Sometimes if he got stuck, we'd just not do math for a while. When he was almost ready to move into pre-algebra (a couple months into 4th grade), we spent time just practicing in order to help him memorize his math facts and get better at paying attention to details. It seemed to work just fine for him, and certainly was more useful than that goofy workbook I got for Collin!
Oh, I also figured out why we're not done with the darn thing yet - you're supposed to do it every day! Duh! Now why would I want to do that? ;P