Learn your PhotoReading skills on non-fiction books first.
Novels we often read for enjoyment and we can apply the steps of PhotoRead and Rapid Read. However a beginner will almost always fall back into the trap of passive reading until they have honed the skills of active reading. So it's unlikely that you'll finish in 1/3rd the tim until you've done a few books using the PhotoReading system on non-fiction books.
If the book is for school apply all the steps of the system. You're supposed to read a novel three times to get the comprehension you need to answer the questions on it. By applying all the steps of the system you can significantly reduce the amount of time required.
Alex