Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Mayank Mishra
For structural geology, Haakon Fossen is one of the best books to clear your concepts. SK Ghosh is also good, but i will suggest you to go for TK Biswal Sir's youtube videos on structural geology. I bet you will never doubt and will never forget the numerical approach to this topic after going through those videos. He is a professor from IIT bombay. Happy Learning. Cheers.