D26 texted a little while ago, said that the AP Precalculus exam is 3 hr long, not 4. She’ll be relieved when that test is all over and done with.
I can’t remember if I’ve mentioned here on this thread before or not, but in case anybody’s kids are interested in testing out of some college classes, you should consider checking out https://modernstates.org/.
They have this “Freshman Year For Free” program where you can take, for free, up to the equivalent of a freshman year’s worth of college courses online through their organization. All of the lectures & practice questions & practice tests are online and you go through them at your own pace. At the end of taking & passing a practice CLEP exam for that subject, they give you a voucher code which you then use to register through College Board to take the CLEP exam for that subject for free.
Honestly, it’s an awesome program and not many people are aware of it. Nor are they aware that a heck of a lot of public universities and colleges (and even some private ones) do accept CLEP for you to test out of classes and get college credit for them. There is some variation from 1 school to another in terms of what classes the college will and will not accept, just like there’s variation on that same thing for AP exams.
D26’s high school requires students to take the AP Calculus AB exam. Math is not D26’s strongest subject. So D26 is going use Modern States’ Calculus course, like D24 did, as an additional way of reinforcing stuff she’ll learn in person at high school during the school year when she takes Calculus AB. Then at the end of the school year, she’ll take the Calc AB AP exam and she’ll separately take the CLEP exam for Calculus through a local testing center (most of the testing centers are at community colleges or public universities, but there is an option to take CLEP online at home). Probably going to have her take the CLEP exam for Psychology, too.
anyway, there’s no gimmick to it. No strings attached. They talked about it last year on one of the “Your College Bound Kid” podcast episodes. Thought I’d pass the info along in case some of you, like us, are not made of money and you have a budget you’d like to stick to for college. 
One should NOT expect any elite college/university to give you course credit for passing CLEP exams, but for any college regardless of its ranking, you should go on the individual college’s website and do a search for “CLEP” and then read up on its policies to find out what your kid would and would not get credit for.