Franklin
I think you might be expecting to much to quick.
Ask yourself if you read a book the normal way how much do you really comprehend. probably on the parts that really interested you. somewhere between 30%-50%
Well with photoreading it allows you to pinpoint those areas very quickly.
Also if you are doing it for a test, the test can't be over every thing in the book.
What i would do is photoread the whole book and then concentrate on the chapters you need for the test. Bye super reading and dipping and then maybe doing it all again. You should at least be able to do it three times faster.
Since this is for a test don't forget to mindmap that should help you tons.