Should Italy build only Zaras and Capitani Romani?

Should Italy have built only Zara-class heavy cruisers and Capitani Romani-type large destroyers?

Yes: those two types best matched the split between protected battle-fleet support and fast, expendable attack craft.

A fleet centered on Zaras and Capitani Romani fit the argument better than one built around many intermediate treaty cruisers. The Zaras supplied armor and eight-inch firepower for work with the battle line. The Capitani Romani supplied speed, torpedoes, and mine capacity in a large-destroyer role. Building both types would make the distinction between durable fleet support and fast attack craft much clearer.