No, I have not been able to nail it down exactly. You'd think that dryer tobacco would be better than moist, but that's not always the case. The pace of your draw has something to do with it, I think.
A very under appreciated part of the smoking process is tamping. You can lose your ember in a heart-beat if you don't tamp properly. And it helps to take a slight draw while you apply the tamper or finger. If you just apply the tamper and then start pontificating on some subject..... you can bet your ass that when you come back to the pipe the ember will be as dead as General Grant......
