i always put them in joints, but never in a blunt. With blunts, i just sort of leave the last 1/2 inch empty.

Why?, because i roll cone joints and straight blunts, so with the blunt, the mouth end is just too big. I have experimented with the "tobacco roach" where you fill the last 1/2 inch of a blunt with straight tobacco, then just throw it away when you get to it.