you can do it with leaves but the amount of oil is low in comparison to dank. the better the bud/herb the more oil. I dont even smoke my bud anymore. i extract all the bud I get and it last me twice as long. When you roast a dove (joint) or smoke it from a pipe or any way that involves burning with open flame you lose about 45 percent of the thc. it gets burned up before you can inhale it and you dont get as much thc. I'm not guessing. pharmacies have proven that with research for me. Not a very effecient way to get high if you ask me. But over all if your having a good time getting high thats all that really matters anyway, no matter how you get there.