I think flushing/ leaching has a purpose, i think flushing aweek before flower when changing nutes is a gd idea, also the soil gets compacted and sumtimes doesnt drain well,and i always watered to run off, flushing in the end? i flushed 20 gals through each 3 gal pot and my final ppm was mid 400’s was hoping for 300 or less, so i dont know, i was feeding pretty heavy, what ever works i guess.