I’m reading this thread a day late, but I wanted to agree with you on Saxon Math. We, too, started 5/4 in 3rd grade. In 10th grade my son tested into College Algebra at the local college so I sent him there under dual credit program for College Alg., Trig, Calculus w/Analytical Geometry, etc. (he had finished Saxon Alg II in 9th grade, we taught math year round, and would just go from one Saxon book to the next, skipping about the first 30 lessons in each book as they are review.)
Saxon Math prepared him well, and to me, the best part about Saxon was if I didn’t think he had a full grasp of a principle, I didn’t worry. I knew we’d see it again next week, and the week after, and the week after. Math is mastered by practice, and Saxon doesn’t leave a concept or principle, they keep reviewing.
I did Saxon until I started math at the community college. I was in calculus there when I was 15. Saxon prepared me for that and for a 740 math SAT score. Saxon’s the best thing since the slide rule.
That is, if you actually do it and no calculators until at least Algebra.
LOL!!! We did the exact same thing....