Yea i noticed the same thing mabey it for vertical growth? i cliped some of my leaves mecause i droped my plant once and teh lover leaves got crushed by the pot but there most likley is an advantage.
i purposly trimed on eside of my baby to do an experiment and the new leaves coming out of the node that the leaves were on are larger than on the other side. i believ that it uses the nutes to build the new leaves at the node instead of making a bigger leaf that wil further decrease the light at the lower nodes. so its for a more bushey plant
when taking clones its best to clip the leaf about half way down, so the rootless plant doesnt have to provide as much water. thats what i do, atleast. i read it in closet cultivator. i recomend that book to anyone new to growing, and some not so new. pretty cheap too.
if your talking about like 1/2 the leafs clipped then it's done to allow the light to lower growth or buds if in flowering.......you only need to remove the part that is covering it, hence only half the leaf, as the other half will still serve the purpose of photosynthesis, and later in flowering it will be used for the nitrogen left in it...........Peace out........Sid