There are so many theories and ways to trim plants that everyone has to find something they think works for them. I just read last week someone here recommend taking off every fan in flower that isn't in a bud, but that's about 180º from what I do in flower.
I've posted this before I think, but the goal of pre-flower thinning is moving growth to the top, and that's when I take both leaves and branches that appear too weak or short to make it to the top in flower (a standard lollipop) like I did here on the Candida. I'll probably have to do it again before I flip since it will be a while yet.
However, when I thin after stretch, I take smaller branches and flowers but not the adjoining fan leaves,
like this. And
here are a few pics of the technique I use when I did it on the Jack Herer. The plant will use those fans to create the sugars to build the buds, and it will draw from them anything it can if it needs to later in flower. If you ever decide to drought in flower, it will need every single fan it has.
I thin in flower this way because I only want larger top flowers with #nolarf. A plant/root system can only support so much bud at harvest, and I want my buds on the top third of the top branches.
I hope that helped in terms of what I do.