Everyone is different, but for the most part, your muscles don't grow any number of hours etc. they grow while you sleep... that is why they say diet and rest is 95% of getting bigger and stronger. If you don't sleep enough... IE train hard, stay out partying days on end, your muscles will not grow.
To sum up its not that complicated:
Train hard enough to damage your muscle tissue...
Eat sufficient protein for the healing process...
Get plenty of sleep so the process can take place...
How fat you get during this process depends on your caloric intake and what else you besides protein.
This is the simplified version of how to build bigger muscles.