Hello Aspirant,

See If you are done with your syllabus of JEE-Main 2021 then solving Previous Year Questions, different Mock tests and sample papers is the best practice to get the thorough preparation of JEE-Main or any other competitive examination, so what I would recommend you is just solve one paper in a day in the fixed time of Three hours and don't go for next paper until you clear all your doubts of previous paper so the concepts will be cleared to you. You can download different previous year's question papers and sample papers of JEE-Main from the link given below :-

https://engineering.careers360.com/articles/jee-main-sample-papers

https://engineering.careers360.com/articles/jee-main-question-paper

You can also check out our JEE-Main Learner's program which  includes the full length Mock test series  and you check out this from the link given below :-

https://learn.careers360.com/knockout-jee-main-april/?product=27

NTA has also given the facility for mock test which you can give from the link given below :-

https://nta.ac.in/Quiz

I hope this information helps you.

Good Luck!!