Grade-wise practice — mixed quizzes drawn from your whole year's syllabus — is ideal for staying sharp and for the weeks before a cumulative exam. It forces your brain to switch contexts, which is exactly what a real exam demands.
Topic-wise practice shines when you're learning something new or fixing a known weakness. Ten focused questions on fractions teach more about fractions than thirty mixed questions ever will.
The rule of thumb: drill by topic during the school term, switch to grade-wise mixed practice in the run-up to exams. QuizPrepHub's library is organized grade → subject → chapter so both paths take two clicks.