I was always of the same schopl as I hear others saying...dont trim em...theyre factories. Ive found there is one really important exception. Underneath those upper sun leaf "factories" there is often a new or young branch being deprived of light. Apoun removing upper fan leafs, you allow light to reach the new shots, which are also "factories"...factories that will develope into healthy buds. I trim fan leaves only once my plants are well established, and there is enough under growth to catch the light that I'm letting through by removing my fan leaves. Removing low growing fan leaves is important as well. The general rule is that if the leaf is not feeding the plant, its feeding off of the plant. That means if its way on the bottom, and not getting any light, then its using energy from the leaves on top. Take those off. You'll know that youre doing the riight thing, because the leave will come away really easily. The plant makes it easy for the leaves and branches that arent feeding it to come away. Ive seen people totally defoliate their fans right as they turn them to flower ( I dont reccomend doing this), and came away with pretty stellar results. I recon that was because every branch on the bottoms which wouyld norlammy be pruned away in an indoor grow, were left in direct light, and able to develope. Alohas. ddiggity