Why Nelson should standardize her dual-purpose battery

Should a late-war Nelson-class modernization combine 5.25-inch and 4.5-inch dual-purpose batteries?

No; the ship should standardize on one calibre, most likely 5.25-inch, to avoid unnecessary logistical and spatial complexity.

A mixed secondary battery would duplicate magazines, maintenance, crews, and handling arrangements on an already constrained hull. The existing 6-inch and 4.7-inch weapons served different purposes, but replacing them with two new dual-purpose calibres would preserve complexity without preserving that distinction. Standardizing on one turret type would use deck space and manpower more efficiently. The 5.25-inch mounts are likelier for their surface punch, though 4.5-inch turrets become plausible once production is established.