Do I have to repeat this every other day?
Do you flush tomatoes before harvest?
Do you flush any vegetables before harvest?
Do they flush tobacco before harvest?
If you have a problem with chlorophyll it's not flushing that's the problem, it's the cure.
Also, most plants start shutting down towards the end of their flowering, and will use up available nutrients at the leaf rather than what the roots sit in. So plants will tend to use up the nutrients you want to flush out.
At this point they are focusing on allowing their flowers to live as long as possible, to ensure as many seeds as possible mature to propagate the next generation.