Air-conditioning units can be roughly the same size while placing their intake and power connections in different positions. Those differences require the surrounding connections to be rerouted. Repeating such substitutions across the ship adds further changes to its systems. Small alterations can consequently accumulate into extensive reconfiguration of the ship's hull.
Notable Point · 1:04-1:38
Why air-conditioning connections can force wider ship changes
Roughly similar-sized air-conditioning units can place intake and power connections differently, forcing rerouting that accumulates into wider changes to the ship.