Why treaty survival would encourage heavy modernization

A counterfactual fleet completes Admiral-class ships, G3s, and Lexingtons in different combinations, including a possible three-and-three split between battlecruisers and aircraft carriers. If a later treaty stopped new capital-ship construction, the surviving Lexingtons would rank among the fastest and most adaptable large hulls available. Their weaknesses would create an immediate list of upgrades, while their unusual speed would make replacement or disposal unattractive. Repeated reconstruction would follow from scarcity as much as from flaws in the original design. Arms-control limits could therefore prolong the service and transformation of imperfect ships.