As for the flushing thing....like most people on here, I'm a novice grower and therefore learning as I go/grow. It's comical to see people post what they consider "proof" be it for or against. It's the age of google I guess. I would say that some fertilizers are harsher than others...and if you are using clean/organic nutes, then flushing doesn't really get you anything.
OTOH...if you are using a harsher nute line, then I say flush....but what the fork do I know?! I grow 4 plants at a time in my garage and (like most here) I'm by no means an expert.