Here’s the problem with depending on the teacher though: they frequently change.
There have been any number of occasions over the years when I’ve received a phone call in August, changing my preps. Sometimes someone has quit at the last minute… in or out of my department. (So it’s possible that someone with dual certification moves over to fill a science prep, for example, meaning that math preps are also changed.) Or that someone goes out on maternity leave and that I’ll cover that class for 6-8 weeks. Or that the teacher who was so phenomenal last year is now facing health or family issues at home and isn’t at his/her best when your child is enrolled in the class.
So while having the right teacher can make a huge difference, it’s absolutely not something you can bank on. I’m certified for Math 7-12, and can teach any math course offered in our building. And, with the exception of Math 8 (somehow), I have.