What is the key factor that increases the potential effectiveness of cross fire?

The key factor that increases the potential effectiveness of cross fire is the arrangement of targets laterally across the unit's front. When targets are spread out horizontally across the front, it enables personnel to engage these targets from multiple firing positions simultaneously without the need for realignment of their weapons systems. This dispersal allows for a greater volume of fire to be directed at enemy forces, creating overlapping fields of fire that can increase the likelihood of incapacitating or destroying enemy combatants.

In contrast, the presence of armor units might provide additional firepower or defensive capabilities, but it doesn't inherently enhance the effectiveness of cross fire. The use of snipers adds precision and lethality but is more about targeted engagements rather than massed fire efficiency. Lastly, while terrain type can influence visibility and concealment, it does not directly dictate the effectiveness of cross fire unless it also affects the arrangement of targets. Thus, lateral arrangement is the critical factor that maximizes the synchronization and impact of fire from multiple units.