I'd pick one book per day to PhotoRead. And use the strategy of working in sections when it comes to activation. That is PhotoRead before activating that section. Only preview the book for 90 seconds. Then treat each chapter as a book and spend a few minutes postviewing, pulling trigger words and forming questions. This is the first activation, follow up with a superread activation to answer a couple of key questions and then skitter. Remember to treat each chapter as a book in itself.
As for PhotoReading PhotoRead the textbook as a whole. Do it sometime during the day. If you only manage to get part way through the book in the five minute commercial break during the news leave the book open. When the next commercials come on go back a few pages and continue PhotoReading till the time is up again. That way you can get through one or two of your textbooks in a day leaving study time for activation.
Alex