A higher treaty ratio gives Japan more ships, not a new fleet concept

How would a more favorable naval-treaty ratio change the Japanese Navy by 1941?

Japan would likely field more of the same kinds of ships, but pushing too far risked losing the treaty and facing greater Anglo-American construction.

A better treaty ratio would probably have produced broadly the same Japanese design choices with more hulls. Britain and the United States would not accept the ratio Japan wanted, which placed a firm limit on the bargain. A failed treaty could leave Japan worse off because the larger industrial powers could continue their own building and technical competition.