Fair enough. I wasn't even referring to a free standing door in the middle of nothing. I was more referring to something like placing a door in the middle of my wall then blocking the backside of the door with steel blocks and iron bar ceiling. Effectively, if the whole path to me isn't vetted for overall health and damage of the path, I can use doors to move a zombie through kill chambers. Least, that's the one thing that pops into my head. Throw some Iron/Wood blocks behind each door for stalling. Or, based on the way it sounds, perhaps concrete, wood, concrete starting from the bottom of my kill path floor. So the total concrete + wood block is overall lower health. Then door behind that to encourage pathing, and another concrete/wood/concrete path obstruction.
Where, simply turning to the right, and bashing through my full concrete wall that's only 1 block deep would be much easier and overall lower health to get to me.