I'm guessing larf is the airy lower buds that are not as mature?
That looks consistent with how I do it.View attachment 1342333
Like in the bowl. It’s just anything I trimmed that looked like it had trikes on it, and also some super airy buds (from the bottom) that didn’t have enough body/density to them to even trim. I may have kept more trim than others typically do — not sure.
My Northern Lights plants were two totally different phenos so their harvest differences may be 100% from that, but I will say the tall girl was way less leafy and more open and her lower buds were much better developed than the short, bushy girl, who had a ton of wispy larf. I'd assumed it was because of way less light penetration, but sounds like that's debatable (like just about everything in growing it seems).In terms of how I do it, if it looks too wispy to constitute a bud - it goes in the trim/larf/popcorn bowl for edibles, squish, etc. I weigh it all.
There seems to be significant disagreement on how they develop. For instance, IIRC @Mañ'O'Green observers that increasing air and light to lower bud sites doesn't necessarily affect bud morphology or trichome development, where others observe something different. FWIW, when I rip a bowl of popcorn (assuming decent cure) I really don't see much of a difference in potency if at all.
Some grows you get nearly all buds, some it's more of a mix like on @indicalla's grow. In my small cab I have hit the max on buds (approx. 5.2 oz) but can get a lot of popcorn depending on the cultivar, the space, and the grow. HTH, YMMV, IMHO, etc.