Did you read the routine correctly?
High Volume Phase
"The training weights will be 58-64 percent of this projected maximum in phase I and 60-95 percent in phase II." http://www.deepsquatter.com/strength/archives/korte.htm
Do however many sets you feel you can handle. Experienced lifters have told me don't let the low percentages fool you.
I did a High Volume Phase a while ago. The 1st day I attempted 8 sets of 5 for the SQ and DL. I completed 8x5 for the SQ. I could not do 8 sets for the DL because my legs were fried. I did 5x5 of each exercise for the remainder of the week and the next 3 weeks.