Jee Main is conducted twice a year- one in January and another one session in April (September this time due to the pandemic), so you can appear twice a year in Jee Main and you can also appear only one session i.e. January or April as per your convenience. A candidate can appear 6 times ( 2 times in each three consecutive years) in Jee Main. For example, if you have passed 12th in 2020, then you can appear in Jee Main both Sessions of 2020, can appear in both sessions of 2021 and 2022. So the total number of attempts become six. Now Jee Main score is valid for one year and in one year two sessions are held. So if you appear for both the sessions in a year, the best of those two scores will be considered for admission.