Flake like HH Old Dark Fired (smoke cured burley) is not very flammable thanks to smoking. I like to cut the flake into 4 lengths and peel half of them into strands. In between cut peices go strands in three lifts. It's kind of like fuses between flake to keep the ember going without too many relights or tamping. I also like to load the pipe 2/3 up with some cut flake like PS Lux Twist or Navy and then top it off with a Tinder pile of shredded flake to start a healthy ember. Never did well with flat stacking or all vertical flake. Just too much work to keep burning without scorching the unburnt portion.