Why cruiser production runs should overlap

When should a navy begin a successor design after a large cruiser run?

For a large force, the later ships of one class should overlap the first ships of its successor, because mature designs are often more reliable and can remain useful longer.

The final vessels of a production run often benefit from accumulated corrections, while the first ships of a new class reveal fresh problems. Beginning the successor before the older run finishes preserves design and yard continuity. It also ensures that reliable late members of the mature class enter service while the new design works through early defects. The approach suits a navy ordering double-digit classes, but it becomes difficult to justify when each run contains only a few ships.