In preperation for an upcoming math test, I want to get through the textbook chapters as quickly as possibly and then focus on past papers. My school uses the cambridge textbooks with the 3 levels of sets of questions (1 being the easiest 1-2 step questions and 3 being the hardest; comprising of only a few questions ~3-5). Should I do all the questions or only focus on level 2 or level 3?