You won't cope with 16 hours a day. You're telling me, You'll revise for 16 Hours still manage to eat, sleep, socialize (If you will), have a shower and do all you need to do in 8 Hours!?
Nope.
I'd advise you spend a Maximum of 6 hours a day. 1.5 Hours for each subject (that's for 4).
Split the hours into the morning, afternoon and evening, and you'll find it soo much easier. Although the time spent is very subjective and varies from person to person.