I used to ask people what they had studied in school, posing specific questions. I tend to be in the company of (former) mid-level or above students. One question was: which writers did you cover in your English/Spanish/Farsi/French/etc. classes? Nine times out of ten, the answer was, "I don't remember." I was a top 1% student and I remember well the writers we studied. No need to ask them about sin and cosine.

But I had to take 6 chemistry exams in college/Master's, and even though I was in the top 1% of students, I remember virtually nothing of anything I studied related to chemistry. And before anyone says "when you open a chemistry book, memories will flood your brain," I did, for multiple subjects, and I saw no flood, only drought.