My dad owned a helicopter business, and we would set fire to thousands of acres of harvested land to prepare it for new planting. Backfiring the boundaries was always part of the game plan so that the heat of the fire would be extinguished along the borders. Heat helps transport a fire, and reducing that heat mitigates the spread into unwanted areas. Looking at the LA City fires and not seeing backfiring along the borders of the wooded areas and the housing developments makes no sense.  Moreover, even clearing brush away from the border would greatly diminish the effects of the fire.  I'm STUNNED that we are this far into the event, and there isn't a wall of people backfiring into the incoming blazes in the wooded areas.  The ONLY way to fight fire of this magnitude is with fire.  You burn the fuel (dry timber) into the oncoming fire to extinguish it.  Using this technique, we would set 5k acres on fire with complete containment with only a dozen people.