If you provide some nutes, might as well give a full diet. Flushing is bro science. Do you see people "flushing" plants outside? No, because that would be absurd.
give water only if you want to be lazy, but don't think it is some sort of value-added behaviour.
Flushing is a tool for a severe problem and shouldn't be don'e whimsically. I'd wager if anything a drastic shift in chemistry for no reason at the end is a net-negative. At minimum it'd fuck with osmosis/diffusion that needs a certain goldilocks zone of concentration gradients inside and outside cells to be optimally effective.