When I compare what my kids get in college with what I did in public schools circa 1990, 7th grade is enough. Education is shockingly inefficient.
If you can write a paragraph, you're ready for the first writing class. Unless you can get AP credit, you won't escape being forced to take that class, so why waste half a decade when you can start immediately? You can probably complete the college classes faster (2 semesters) than pre-college schooling would take you from "can write a paragraph" to "scored a 4 on AP English Composition".
The same goes for math. Knowing a bit about fractions and decimals is enough to start. You can skip the first college class if you can simplify expressions, solve sets of 2 equations, and deal with inequalities. Skipping anything more would require AP Calculus, but that still wouldn't get you out of the math credit hour requirements. You might as well just start college earlier.
If those college expectations sound like high school or lower to you, then you're old and you're starting to understand. College is the new high school, if even that. We decided to pass all high school students, with "individual education programs" as needed to avoid maintaining standards, and to expect everybody to go to college. This is the result.
Further, there's a difference between 'getting by' and actually gleaning the value of the education. People who took analysis and university level linear algebra got much more out of discrete math than I did, even though I scraped out a decent grade.
I've seen similar situations in community college. It's possible to barely pay attention and glide through the whole thing, but there's often a decent education for the taking if you put some work in and engage.