Sherman tanks provide a comparison for the Bretagne class's different machinery installations. Multiple engine packages can be supported within a very large production run. Giving each of three battleships a different boiler arrangement produces variation without comparable scale to absorb it.
Notable Point · 1:35:38-1:35:59
Why varied Sherman engines differ from varied battleship boilers
Several engine types are easier to justify across mass-produced tanks than across three individually different battleships.