It(15 hours) is definitely a long time to be sure, I often have to do other things in the course of it(such as walk the dog or get up and stretch or eat) but I am always thinking about the study. It isn't the Norm though, I usually only get into it like that when I am studying and making a study to help out someone else.
2 Hours is a long time to study every day, most of the people I meet barely get 30 minutes of in depth study a day. So it's nice to see someone who is diligently seeking the word through study.
What are your favorite stories from the OT?
Mine are the stories of the Ark being taken in 1 Sam 5-6 and Elijah Mocking the priests of Baal in 1 Kings 18.