NODIE: That's not true. The plant to regulate the internal temperature of the nutrient uptake will grow the large fan leaves. MJ will grow best with in narrow, given temperature range so if the grow room suffers from high temperatures for a period of time then you will get larger fan leaves to compensate. With cooler temperatures the fan leaves do not need to be as large and if you can keep the temperature swing within 5° (+/-) of 75°f over 24 hours and through the entire grow cycle you will have leaves that are all about the same size.

Fan leaves do serve a good purpose so leave them alone. Tuck them under but do not cut them, you could raise the internal temperature of the plant and send it into shock.