At Least How Many Tests Should Be Taken For The UPSC Mains And Prelims? It Depends on How important time You have UPSC Prelims Mock Test. As the Saying Goes, Revise the Basic till the Last Nanosecond, that’s what you have to do. Modification just not by reading it again & again but by Giving Mock tests so that you can dissect your Retention capability & Also learn the habit of Intelligent Guessing specifically for Prelims.