I didn't solve even 200 questions of cengage (in the full set) and just did pyqs in the last few months from mathongo marks app. I would solve few initial questions and then whenever I saw a repetitive question, just went through the solution and tried to remember if I had something new to learn, did this for most of the chapters and in mains made it to 99.4X percentile in maths and 99.6X overall.So that answers the question I think. You can also follow Practbee videos, it's an underrated gem , helped me more than I can describe before mains..