Previous year questions show the idea the exam already asked. They are more useful when you can see why your attempt stopped.
Work the question first. Upload the steps. NuRhoN marks the first break so the next set stays on that concept, not on a longer list of papers.
One question, one gap
A previous year question often mixes two ideas from the same chapter. If the first idea holds and the second slips, the tag tells you which one to practise. Personalized practice then stays on the weak idea.
You can save the attempt and resume it later. The paper does not have to be finished in one sitting for the diagnosis to be useful.
Keep the year beside the chapter
Use previous year questions beside chapter practice, not instead of it. When the same concept fails across years, that is the chapter to revisit with a short quiz and a solution at Beginner, Medium, or Advanced.
When the steps hold, move on. Collecting more papers does not close a gap that one clear step would close.
What to look for in the working
A conceptual miss means the idea itself is not steady. A procedural miss means the idea is there and a step in the method is not. A systematic slip is the mistake that keeps returning in the same kind of question.
Name that pattern before you open the next paper. The previous year question has done its job when it points you back to a specific chapter, not when the score looks finished.