I personally know past college admissions directors of good colleges. In general, students who are applying to the Top 25 schools should aim for 5-7 AP classes at most (no need for 10) with a focus on APs directed towards the student’s academic “theme”. For example, if the student is going to study chemistry in college, there is usually no need to take APUSH. Likewise, the English-themed student would probably be better off taking AP classes in the humanities instead of AP Physics or AP Computer Science. At the top 50 schools, taking no AP classes will put the applicant at a severe disadvantage. Taking 2-3 AP classes by the end of 12th grade would be advisable for anyone applying to a college ranked in the Top 25-50."
He is a STEM major so no need to take AP English. Our high school is a highly ranked college prep school and there are the students who take too many APs, just for more rigor, not knowing that it’s unnecessary. And of course, they aren’t interested in them, just going through the motions. Some who overloaded had their GPAs suffer and ended up at lesser schools than their goals. Others end up dead from suicide or have breakdowns, but all are stressed and sleep-deprived. There just isn’t enough time in the day so sleep suffers.
Your son should finish in BC Calc if he is going to be a math major.
Be sure your son writes at least a rough draft of his college essay(s) during the summer prior to senior year. Working on it along with schoolwork in senior year is stressful.