["Bone to Bark" BBQ]

Think of your charcoal basket as an oversized chimney. Most offset cookers draft upward over the coals, sort of diagonally from lower outside to top inside near cook chamber. Once your coals ignite from a corner, your load of fuel is burning from bottom to top, which decreases burn time. Unless your charcoal is spread out in a thin uniform layer, burning from end to end, don't expect more than a few hours of consistent temps. Unfortunately, you can't get that set up in an offset. The exception is, UDS charcoal baskets where the Minion method starts on top in the center, and burns down and outward.