The 'fan' leaves that we all refer to have a whole host of other names on other plants and in other circles. The name 'sun' leaves is also common. We're dealing with a flower here. One of the reasons that flowers produce their flowering shoots on the intererctions of leaves and stems is the internal structure of the plant. It places the most important part of the plant in the most convienient place to obtain its nutrition. Simplified even further you are dealing with a small solar collector. Every square inch of photosynthetic tissue you remove is either a loss of energy input, or something that the plant has to work harder to grow. Plants arent growing with the thought of getting you nice big buds. They are growing to produce enough viable seeds to continue it's species. One plant that produces 100 seeds has more than done it's job. Removing large sugar factories (the leaves) is one certain way of slowing down the plant. Pick up a biology books and look up common plants. No disrepect to anyone, but the only time that the plant isn't really using that much sunlight is once the large fan leaves start to yellow and drop the week before harvest or so. That isn't to let light in to the flowers, they are nearly if not totally mature. It's simply because they aren't needed anymore. If you look at any plant in nature, they do not grow unnecessary structures, it is a tremendous waste of energy. Nature is incredibly efficient, and even though most of us are going to very unnatural steps to produce our fine products, it's still a plant and follows those rules.