Unless you have mega penetration from a huge well lit and reflected room, I would always advise removing what usually becomes "popcorn". So all the lower bud sites.
I don't get why you would remove the lower fan leafs really? Surely can only grab any of the leftover light coming through the canopy. If they ain't getting light they'll come off themselves into flower.
I am extremely intrigued by these growers doing FULL defoliation of all fan leaves at flip and then 3 weeks or so into flower. Some of the results are super impressive. Massive yields, but they are in super dialed in enviroments, much much more so than most of us home growers. Also will likely be strain specific how well the plants handle it.
I am going to try removing top most fan leaves on my next grow to try densen up the bottom of my canopy. But I am skeptical, considering I have always thought of fan leaves as essentially the solar panels of the plant.
It really depends on growing method aswell. If you are Scrogging and have built a dense canopy, I would only leave the top 18 inches - 24inches at most, of bud sites under a 1000w HPS. Anything below this will be fluffy in my experience. I pretty much always regret not removing more bud sites from the bottom come trim time.