People practise content but they don't practise test techniques. The key criteria of tests are that they are unpredictable and timed. The work done in class and the homework based on class work is always predictable and rarely timed. Effective practice for a test will come from attempting unpredictable work in a timed scenario. At home, unpredictable questions might come from a different text book or past exam papers. Then you need to self-enforce a time limit during your practice. For exam practice, we are lucky to have past practice tests available for students to work through.