I always use a mini chimney over the burner tube for everything except a pizza cook - then I use a full size chimney.
Normal practice is to add whatever amount of briquettes to the mini chimney it will take to fill the baskets that still hold leftover charcoal from the last cook. Light the gas for a couple of minutes, then let the chimney go until mostly ashed over, then dump half the chimney into each basket.
I'm usually only using 10-20 new briquettes and a chunk or two of wood each time - a bag of charcoal lasts a long time.