I think that's just going to confuse and stress them, as Northern said, they're done when they're done. You can't trick them into finishing at the same time.
I do 24 hours dark before flower. I dont have a good reason. I guess, when I started doing it I thought it would help them "notice" the time change... sounds dumb now that I'm explaining it.
I also used red light for an hour and a half overlapping lights on and off to simulate sun up and sun down to indicate 'got to sleep and wake up'
Lights do things to plants. Might be subtle but things happen. I dont mind if nothing is coming from it, nor have I had the resources to do a controlled experiment about it.
Lastly, I do 48 hours dark before harvest. And I cut before the lights come back on.
check this light cycle out for 100% sativa's _ veg at 12/12 and when you flip to flower give 24-36hr dark time then flower at 11/13 basicly doing a dark time before flowering will shorten flower times by 2 weeks
check this light cycle out for 100% sativa's _ veg at 12/12 and when you flip to flower give 24-36hr dark time then flower at 11/13 basicly doing a dark time before flowering will shorten flower times by 2 weeks