In many cases, it helps to mix up your self-testing. Don’t just focus on one thing. Drill yourself on different concepts. Psychologists call this interleaving. Try to solve problems and recall information on your own. Then check to see if you’re right. Retrieval practise boosts your learning and memory. Actually, your tests usually will have questions mixed up, too. More importantly, interleaving can help you learn better. If you practice one concept over and over your attention decreases because you know what’s coming up next. Mix up your practice, and you now space the concepts apart. You can also see how concepts differ, form trends or fit together in some other way.