I use Dutch Masters and usually roll the blunt with a gram if it is just me and another person, more depending on who else is smoking. Standard burning time is 15-20 minutes when rolled properly, tightly and evenly. To help the burning I try to give mine a cone shape by spreading the bud out so there is more in the front and gradually less on the hitting end. Honey can also be used to seal blunts and supposedly make them last longer, I've never actually bothered to time a blunt rolled with honey though.