Depends. If the 5 books will answer each of the question and it doesn't matter which book it came from. The Syntopic reading with your purpose in mind would probably be the best option.
However if the answer to each question can only come from one book at random. I suggest allocating at least 60 to 120 minutes with each book with a strong purpose for each. So spend 20 minutes on each book each day for the next 5 days... use a similar technique to the 5 day test for each book just reduce the time to 20-minutes.
Alex
