Khan Academy is fantastic for developing foundational skills in AP courses. But you're kind of left hanging there. Because all the questions are for the most part supposed to be assessing a singular skill, it's kind of difficult to prepare yourself for AP exam questions that asses several different skills. Not only that, but the restriction of each question only focusing on one skill also makes it difficulty to prepare yourself for the medium- and hard-difficulty questions on the exam.

I was thinking that some assessments (quizzes, unit tests, course challenges, and possibly mastery challenges) would have their own unique questions that would focus on several skills in one question. Also, there could be an SAT-esque system where if you do well on the easier difficulty questions, you can get more difficult ones.