They should be. One of the nine U.S. Army Principles of War, our bedrock doctrine, is Unity of Command: for every objective, ensuring unity of effort under one responsible commander.
Failing to follow this Principle can be a recipe for disaster.
Great post. I intend to take a very close look at those nine principles.
http://www.wpi.edu/academics/military/prinwar.html
Mass:
Concentrate combat power at the decisive place and time.
Objective:
Direct every military operation towards a clearly defined, decisive, and attainable objective.
Offensive:
Seize, retain, and exploit the initiative.
Surprise:
Strike the enemy at a time, at a place, or in a manner for which he is unprepared.
Economy of force:
Allocate minimum essential combat power to secondary efforts.
Maneuver:
Place the enemy in a position of disadvantage through the flexible application of combat power.
Unity of command:
For every objective, ensure unity of effort under one responsible commander.
Security:
Never permit the enemy to acquire an unexpected advantage.
Simplicity:
Prepare clear, uncomplicated plans and clear, concise orders to ensure thorough understanding.