hi harsh,

I think you scored 95.7 in your 10th class. That's great!. You need two important qualities to crack any exam: Be HARD WORKING(it seems you are already a hard person) and BE PERSISTENT(continuous effort is the most important thing to crack any exam). I don't want to discourage you but many students can't get persistent during there preparation journey. Studying for long no. of hours is necessary if you want to complete the vast syllabus of JEE but study long with full concentration. If you can't study with full concentration for 18 hours. It's okay. Reduce the time to  12-14 hours and you can revise in your free time. Also to know whether you really understood the question do same questions multiple times.

I hope this answer will help.
All the best for the future!!

Hello dear

95.7% is a very good score. And one thing i let you kow that there is great difference in school and jee I am not discouraging you but it's a reality.

18 hours is enough or I can say more than enough for study. But you should study qualitatively means what you study do it in perfect way and you should take a test series in which you can analyse yourself and if you are doing well in the test series than you will definitely do good in exam also. But as seeing your dedication you definitely get a good rank and I would suggest you to reduce some hours of study ( 1-2 hours if possible) and do some exercise  which will keep you healthy and you will get relaxed and concentration in your studies and don't get panic till the end even in exam.

Good luck.