I think they do ignore it, at least if you don’t fall into a hooked bucket. Whether it works is debatable, but a lot of parents want their kids to go to an elite BS because they believe it will improve their college admissions. We’ve had former ivy adcoms on here say the student who got a 4.0 at some random podunk high school is going to be treated as less impressive than someone who got a 3.9 at a top notch public hs known for academic rigor. If anything, going to a less impressive high school, hurts not helps, the unhooked applicant.