Hello Vishesh Vyas 

Actually according to my knowledge of you study well for 9-12 hours also it is enough but the thing is you should study with most dedication 

Yes if your having the particular goal to be reach for sure you will get success and also you will study 12-14 hours it is not at all problem for you 

Don't waste single minute of time while studying

Please follow the proper time table 

Don't divert your attention from the studies to other activities 

All the best