My two pence. fan leaves collect the light, buds do not. I have run an experiment in the past with two plants after harvesting the majority. The plant with fan leaves kept growing and maturing, the plant with just sugar leaves and bud, it died, quite quickly.
The fan leaves collect the light that the plant uses to grow the buds. People seems to have this idea that they are trying to grow buds not leaves during flowering, no, you are trying to maintain healthy foliage which in turn will produce the buds you are looking for. You can certainly cut off fan leaves here and there to aid light penetration to lower fan leaves if you wish, or remove fan leaves to aid air movement, but there is no positive reason to be trimming off fan leaves.