I think the main thing here is that while the idea of moving without disengaging works out fairly well while dealing with only two opponents in a functionally white room - the scenery being meaningless outside of stunts - it stops working well when there is some third point involved. Your two swordsmen fighting, if one is following as the other moves, are changing the distance they are from the archer shooting at one of them, unless he is also supposedly moving as the two swordsmen move. It's simple trigonometry. This gets further complicated if one of those points is realistically stationary,...