Sara,
My intention when just reading the black letter law is to 'find the principles or concepts which are at the root of the area of law I'm am studying.'
For example, during a trial I had to fully utilize the code of evidence. My trial was against an older lawyer who had more trials than I had.
My purpose was simple: "What rules of evidence will I really need to keep opposing counsel's evidence out and allow my evidence in?"
I already knew what evidence I needed for the jury to see and hear and what evidence I needed to keep away from them. So, I used the whole system. When I came to the superreading and rapid reading, I knew exactly where to focus most of my time.
After I had fully understood those black letter laws, I went back and photoread the cases or annotations that went along with the laws. I then re-stated and refined my purpose as 'What principles or concepts are at the root of these black letter laws?'
I slept on this question overnight. When I awoke, I went on to try my case. During the trial, I could explain to the judge why my evidence should 'go in' and my opposing counsel's evidence should 'stay out'. I made very convincing arguments and easily won the trial.
Keep it up and do well,
-CS