with baccos like tangiers which need less heat, i would try double foil.
also if your a newbie in the smoking field 2 layers will be easier because your taking in more oxygen, and it also burns less tobbaco.
it does make the bowl last a long time, but its doubtful ur gonna be smoking too many coals or else you would know alot more about hookah shit.
my friends do double, even tripple tin foil to make it easier.
i only use double for tangiers so it gets less heat, but nethign else ill just use 1 coal.
hope u have a good smoke man.