Today I'm taking down a room of NYCD, at 10 weeks flowering. Some of the room finished faster than the rest, due to a dodgy green light. I'm now satisfied that it's finished enough, so down it comes.
The half of the room that finished on schedule has been flushed for a week. That was 2 waterings. The stuff taking longer has not exactly been flushed; the last watering, it got water+Cha Ching, a fox farm product, and a "sweet"-type product. I wouldn't exactly call that a flush; it contained some nute, rather than just plain water...
I'll soon see for myself. But I think flush is great: if your plants are a week or so away, they probably don't NEED nutes at this point, so you might as well just feed 'em water. It costs little to nothing (certainly less than feeding them nutes), involves zero extra effort, and is harmless to the plants and the flavor and smokeability of the dried, cured product. In fact, I can't think of one good reason NOT to flush. Unless it's important to you to prove strangers on the internet wrong.