Why fitting for upgrades does not guarantee installation

Is leaving warships fitted for but not with equipment defensible if systems can be installed later?

Only with risk, because wartime or maintenance pressure may consume the yard time needed to install the deferred equipment.

The exchange compares modern frustration over under-equipped Type 45 destroyers with the County-class experience of incomplete armor upgrades. Reserving space and connections can make a later installation technically possible. It cannot guarantee that the ship will receive yard time when the fleet is busy or war creates more urgent demands. A fitted-for-but-not-with plan remains a real capability gap until the equipment is installed.