How important are fan leaves to flower production?

[NAKEDGARDENER]

I only remove leaves which are damaged and or old, I tend to think the plant has those leaves for a good reason, taking some off now and then to allow for airflow, as far as I am aware they are the energy devices, I used to think that super defoliation was a technique that was good, I now think it’s hokum

[growsomebuds]

I've been removing fan leaves from my plant, here and there, during the month it's been flowering. I've been doing this to maintain good light penetration. The pics you see is after 15 days since switching to 12/12 lighting. Are fan leaves critical to good flower production? Is it best to leave most of them alone during flower?