question about flushing

i'm using biobizz organic nutes and bio bizz soil near so the end of harvesting few weeks to go just wondering if it is nesessary to flush using organics, or when should i start flushing opinions please ...

i grow all organic and flush last week and a half or so, sit your ladies in the bath tub and pour twice as much ph'ed water as the pot can hold.

how many times should i do that in the last week and a half or so .... just the once or like every few days ?