It’s only about 4% THC so you need a lot of leaves. Stems are surprisingly good: Just picking fan leaves off my BD bud stalks, I get a large amount of resin on my hands. You can rub your fingers together and form black resin balls. You can wash it off with 70% isopropanol and collect the washings in a little dish. When it evaporates completely, you have hash.
The little sugar leaves people trim off the buds are not nice to smoke, but they have a LOT of THC on their surface. Ideal for making oil if you don’t have poor relatives who want to smoke them.