Make a feature where you can choose which topics/units you want to practice together rather than the only option to practice them all at once. For instance the feature would include which units/topics you would want to do more studying on. If you don't know a few units in your AP course too well you could study them together. Like for AP Art History or AP Environmental Science when you do the multiple choice practice questions you can choose to practice questions from unit 1 and unit 2 together; or unit 4, unit 3 and unit 7 together or unit 5 unit 8 and unit 2 etc... ,You can have the option for which topics/units you are not too familiar with and which ones you feel like you need more practice with.