When I was first learning how to house dance in 2000, I practiced about 2-3 hours a day almost every day. Nowadays, I don't practice as often - most of my "practice" comes from teaching or dancing at clubs - but every now and then I'll session for a little bit, particularly when I want to expand my vocabulary or fix my form. My typical practice session consists of freestyling, working on 1 or 2 new moves (I think I was just learning how to do the "set-up" in the first video), and working on my form without compromising my dance/groove too much. Oh, and making sure my pants don't fall. Don't ever limit your practice time to mere drills; remember, you're a dancer, not a machine.
From March, 2009
From October, 2011
In both these practices, I danced to the songs for the first time. After you get more experienced with musicality, you'll develop a sense for what's going to happen next in the music. Notice also how I matched the feel of the music by dancing harder on the first video in comparison to the softer music on the second video. While at first you may have to do these things consciously, with time it becomes second nature.