They actually last quite a while. As odd as it is, I've had better results using the chimney on the gas assist followed by dumping the chimney into the baskets/grate. It puts the fully engulfed charcoal 'on top' and the partial (or unlit) on the bottom. The baskets are kinda big to get an even ignition compared to the chimney. Once the bottom 1/3 or so of the chimney are lit, I turn the gas off and let the chimney work it's magic. Since I started doing it this way, I really slowed down on the 1 pound bottle swaps. Still, best to have extras on hand for obvious reasons.