I had subbed at our local elementary school, and they used Saxon. That was how I discovered that I had opinions about how math ought to be taught.

Lots of people already know, but I’m just saying aloud for the studio audience-- there are two approaches to math. One is the spiral method; the other is the mastery method. With programs like Math-U-See that use the mastery method, they focus on one thing at a time… you start with single-digit addition, and get good at single-digit addition. You do single-digit subtraction, and get good at single-digit subtraction. You do double-digit addition, and double-digit subtraction, with a little bit of time-telling or whatever thrown in for good measure. But you don’t proceed on to multiplication until you’re solid on your addition and subtraction, and you don’t proceed on to division until you’re solid on your times tables, and so on. It’s very structured and organized and focused, and you get that repetition until you can do it forwards and backwards.
The spiral method, which Saxon and others do, is more hodgepodge scattershot. You do a little bit of patterns, a little bit of fractions, draw pictures to illustrate word problems, do a little addition, a little subtraction, a little time-telling, and so on. The theory is, you do that for a certain period of time… and by the time you hit the 6th grade, you’re fluent in all of it and can move on to pre-algebra.
But for my kids, they just weren’t getting enough focus on the basics to get them really solid. If I hadn’t done homeschooling for pre-K/K, they would have been lost. As it was, they were able to coast a bit… but I still had to trot out the math at home on top of the homework they got sent home with.
I’ve subbed high school as well, but it was calculus, and it was mostly “program your calculator and write down what it spits out” class, so my involvement was mostly limited to roll call.

So I’m not too sure on when our local public school system transitions from the a-bit-of-this/a-bit-of-that approach into the focus-on-algebra/focus-on-geometry/focus-on-trig that I remembered from my schooling.
My kids really liked the manipulatives that Math-U-See uses— they helped make the abstract less abstract, but were way better than the school’s manipulatives. And the DVD lessons were great!