I think the speed reading class I took at lunch in high school was one of the best things I did. Reading is a eye brain skill and even very good readers can improve their reading speed considerably with only a slight drop in comprehension (and many things, including literature, don’t need 100% comprehension). Obviously, slow reading or poor comprehension needs to be corrected as soon as possible.
My high school had a 10 book summer reading list, which I thought was great in that we only had to reread parts of the book for our on-class discussions and essays. And this class was way beyond the AP prep classes I see now (and I got a 5 on AP English).
CMU story is true at another top engineering school. I am sure the reading / writing expectations at a top 20 school for an A or even B would be very high in other majors. So not only do you need to push yourself to get into a top school, but also to do well there.
I would certainly try to stay with vigorous classes that insure good math and reading/writing preparation in high school.
Google makes a lot of the busywork go faster on research, and you can find approved sources (not wikipedia, but that usually makes for a good overview you can use to make sure you are covering the basics) that way and use them in your bibliography (a lot quicker than scanning the stacks and looking for references in a book). Efficient research including locating people who can help you, teachers, peers, tutors is another skill you should learn in high school.
Dialing back from 2 AP classes in sophomore year will not take you out of the running (pun intended) for a top school, it’s pretty aggressive.
Naviance and discussion with your guidance counsellor on typical outcomes for their top (is top 15 APs or 8?), top 10%, top 20% students for example in UC and CSU admissions would be very helpful. Now is a good time, before you need to commit to a junior year schedule.
I will say in junior year, no top student has free time or time for 10 hours of sleep. Everyone is pushing hard. Senior year, many students dial back because they feel the race is over.
XC at JV level is not exceptional … you don’t have to do any sport but would have to replace with a quality EC. I might actually recommend that, but you can’t do debate team and skip gym credit.
Number of AP tests taken is a metric used to rate schools. I believe it is tests, not courses, which is why my daughter was encouraged to take some low score tests and missed out on AP National Scholar. I don’t think our APs were exceptional or ridiculous amounts of work, but lots of 3s and 4s, not many 5s.