Any book and a variety of books so that you photoread 4 to 10 books per day is the way to develop the mastery of photoreading as a whole.
Photoreading only the dictionary limits it to improving your vocabulary but does not expose you to the talking style of various books. Photoread the dictionary once or 2 times a day(for improving vocabulary) and add 2 or 3 other books to photoread and your photoreading skills will develop faster.
Alex
