How does Flawless Finish by Advanced Nutrients actually work on the flushing phase?

Day 55 going on day 56, I've been watering them with 5 gallons of plain water for each one for the last 4 days, I've done that twice. I want to add Flawless Finish sometime soon but what does it really do? I have a ton of fresh bone meal in there. So how does it actually work in aiding the flush?

Flush yer toilet not yer weed

Feed your plants man

This is a study that has shed some light on the subject.