This may be an old wives tale...I've seen no noticeable difference even if you leave them off for 4 or 5 days and then harvest. That's just me and the strains I mess with. I have a grow bro that insists on doing this and I don't and when we compare stuff grown from the exact same clones, exactly the same amount of time, there is no difference I, or he, can detect. Have at it tho and see if you can prove it one way or another...I think it's two or three days wasted to do this however IMHO.