Hi Nicholas,
you do have the option to practice with less questions. Two modes are avaialable: in the timed mode, you choose how many questions you want to answer (up to 100), and the available time is adjusted accordingly; in the learning mode is very similar, but there is no time limit. In both cases, you can select which knowledge area(s) to focus on, and whether you prefer to have questions on ITTOs or not.
The attached screenshot shows you the options mentioned above.
Gabriella