Iv tried this on 3 separate garden grows side by side others, 24h/48h/72h, no difference what so ever, one thing i will say is the last time the lights go of that night and your harvesting the next morning just turn them off so they dont come on as iv heard harvesting them when the lights come back on can degrade the THC quality, no idea if it is true but i just do it for the sake, hope this helps buddy and happy harvesting!