when you flush the plant, it gets rid of all the starches and sugars that the plant stores during the day, when these are still in the plant when it dries, they cause your smoke to have a harsh and bitter, not smooth taste.
you can tell when your plant has been properly flushed by snapping off a small stem and tasting it. if its bitter, keep flushing.
harvest at night before the lights come back on. all the starches, sugars, chemicals etc are down in the roots at night and you'll get an even better smoke .
so if someone said flushing isnt worth the time, that might be what their talking about, but its still not good enough for a decent smoke.....flush and harvest at night and you'll have a great smoke.