Like others have pointed out, it would be good to accelerate if the student can get A or A-. Otherwise it's better not to accelerate.

My observation is that ivies occasionally take some well-rounded kids. Our application will focus on top 25 school, not necessarily ivies. But will apply to a couple of ivies just in case luck hits us.

D26 is on stem track. She is taking all advanced stem courses in the school, so far all As or A-s.

Taking Advanced Calc in 11-th grade, and linear algebra in the 12-th. Private high school. Overall GPA reasonable with a few B+. Her school does not give weighted gpa for advanced courses.

How colleges view the rigor of her courses, given that the school does not provide ranking and does not provide weighted gpa for advanced courses?

At a school like NCS, 3.3-3.4 is right around the median GPA. This is cut throat.
However, their eximission tells a different story, a large percentage of students went to top colleges.

Does anyone know how GPA in private school is viewed by top colleges? GPA in private school is typically on a 4.0 scale, fewer people get A per class. As a result, GPA in private school is much lower than its counterpart in public school. For example, a 3.7 GPA (A-) in a private school might translate to 4.0 in a public school. But the question is how top colleges view a 3.7 GPA from a private school? Nowadays it appears every top college requires 4.0.