Cracking jee advance does not depends on how much hour you study every day.
It depends on how much you study with your full strength. You have to follow your time- table very strictly to crack jee advance. You must have also good knowledge about time management skill during exam time. It will helps you a lot. It's not all about studying whole day.
Hope it helps.
This is not about how much hour you study,you just have to be punctual and efficient.try to make schedule for everyday and follow that schedule,try to attempt mock tests that would definitely be helpful for you,solve previous year.
A perfect and smart schedule can help you more than anything so try to complete your scheduled task everyday.
IIT/JEE 2020 Online Preparation
Crack JEE 2020 with JEE Knockout Program, If you Do Not Qualify- Get 100% MONEY BACK
The point is If you study with dedication then self study for 4-5 hours per day is enough but If you don't study with full dedication then studying for even 15 hours per day will not be beneficial for you in clearing JEE Advance.
Still If you ask that for a normal student that How much hours he/she should study per day, then I would say that self study for 7-8 hours per day is enough.