I am going to place firebricks wrapped in heavy duty foil in the bottom of my COS to help with heat retention and distribution. Originally my thinking was to place 3 bricks end to end from right to left and then have a sand pan heat sink before the firebox. In looking at things though I could place 5 bricks or so width-wise from right to left before the sand pan. Would this give me better heat retention and distribution? Heck, is the whole firebrick thing a fallacy?