First hand knowledge, my DS15 is is H.S. My older DD is at university. My kids attend/ed at a top "highly ranked" public high school that sends kids to Ivy's and top schools. The pressure at our H.S. in these top schools is intense. I know kids who gets these top scores, I see what it takes out of them and how hard they work. And what the teachers expect and how they grade.
My husband is a professor & many of my friends are also professors at a large public university. I hear frequently about how while the GPA to get into the school is getting higher and higher, the kids are less and less repaired for college level work despite taking oodles of AP's.
