When they're ready I switch off the lights and maintain temps but a dodgy back prevents me harvesting in one day so the normal is doing a plant or two every day or second day depending, week between the 1st cut the last isn't unusual and I can't tell any difference.
Flushing at best will empty the plants vascular system it takes 3-4 days if a bluelab truncheon is to be believed, I've total faith in it personally but that's not say it actually makes a difference... Old habits and all