A battlecruiser adds to a battle line but cannot safely replace one. If industrial capacity cannot provide enough battleships and battlecruisers, the navy should build battleships because those ships must stand in the decisive line. Ordinary cruisers can still perform much of the reconnaissance, commerce-war and trade-protection work assigned to battlecruisers, even if they do it less powerfully. This force-structure logic makes the Japanese speed-first concept more exposed than a balanced fast battleship.
Notable Point · 58:34-59:35
Battlecruisers only make sense beside enough battleships
A navy without the industrial capacity to build both types in useful numbers should prioritise battleships and let cruisers cover most specialist missions.