This year, we just used time4learning.com, online math games, flash cards, and math board games for our math program. They both finished their math for the year a long time ago and started working on the next year's level.
We used Saxon the first year and it started out OK, however, it got very gruelling. Every day, math took 45 minutes to 3 hours just to get the kids to complete it. (and that was not doing every problem.)
We used Rod & Staff the next year, and it was very flat and not a very advanced math. They did it, but we stopped almost at the end of the year.
I attempted Bob Jones, but my daughter started out failing, so we switched curriculum and went back a grade. Never did go back to the Bob Jones.
This year, we are switching (and staying unless it's just really terrible) to Math U See... I'm so tired of having poor experiences with math.
We just finish when we finish, I don't do lesson planners or calenders or whatever. I kind of prefer not to have a definable school year, so I'm not on a deadline of any kind. Remember that you aren't obligated to do every single problem or page. Do what you need, leave the rest. Curriculum is a tool, not a master. I'd like to add that no ps teacher I've ever known ever finished a textbook.
With teaching textbook (math CD on the computer) we would have been done a month ago if DS hadn't gotten stuck on a few chapters and had some other family issues. The way life has happened...we MAY finish by the last planned day but maybe not.
I think it depends on your curriculum and how quickly your child catches on. With Math U See it's a mastery based program so we don't even move onto the next chapter until the previous one is mastered. Some chapters took a day or two, while others took us a few weeks...
We use Saxon for Ds1 and we will finish it just it by the end of the week and we started in August. We do one lesson each day and do about 15 of the 30 mixed practice problems, unless he has trouble with a particular kind of problem.
It takes anywhere all year to two years to go through it. I also use the life of fred as well though. My son likes to play with math so some days he just has fun with math and reads the life of fred. Honestly I don't pay much attention to how long it takes. My main focus is more on the enjoyment. We use teaching textbooks and love it.