You will certainly have very good subconcious understanding of the material. For instance, Paul Scheele speaks about PhotoReading a dictionary and someone scoring better on the vocab section of the SAT. However, there is no activation of the dictionary. Same thing with photoreading a manual to help you become better at a sport or something.
However, if you want to know the information in your History Textbook, for example, simply photoreading it for two months will not give you automatic concious understanding of the text. That is why the activation part of the system is provided. It lets you decide how much you want out of a book.
Hope that helps.