I was taught to cut the leaves down in the 90s as it helps them to put more energy towards the roots.This comes from what is known as The Bible of Cannabis Horticulture "Indoor Marijuana Horticultural".Which sold over 1 million copies written by one of the most trusted names in the industry.Jorge Cerventes.If I remember its to stop the transpiration as it takes a lot of energy,it was 30yrs ago but you see all the industry big wigs do it along with the big grow ops in Cali so I know who I listen to.Where did you hear it from?