Daily 3hours study is most recommended with each subject getting 1hour each. On weekends double this to 6hours with 2hours for each of PCM. 

In college and tuition you must sopve doubts and while travelling you can revise. You should set time table and optimize time to do smart work. 

Understand weightage and syllabus and study accordingly to remove redundancy in some sections. 

Hello,
There is no certain time boundation for how many hours you want to study.It totally depends on you that how much you want to give time to those subjects.What i meant is that if you are able to or capable of completing a topic in 2 hours then it useless to give 4 hours.So, what i want you to understand is that work hard but also work smart so understand what time it will take to study for you.If it takes 10 give 10 regardless of any hesitation.
I hope this helps.

Min. 1 hour each for every subject.