It is a bit of a grey area, and necessarily so. Because there is no single correct answer. Your body, strength levels, recovery, and your goals all contribute to the decision making.
I was scaling back an fsp if i saw large volumes of it in the wod. But i found it didn't work for me. At this stage of my development I've decided i need the fsps to be my consistent foundation upon which the wod is building.
So i always do the fsp as scheduled and modify the wod if necessary to suit.
Many people do the opposite, which is equally valid.