What earlier controllable-pitch propellers could change

What would reliable controllable-pitch propellers have changed if they were available during the Second World War?

They would probably have made warships faster and more fuel-efficient, with the efficiency gain extending range.

Earlier reliable controllable-pitch propellers are expected to improve both speed and propulsion efficiency. Better efficiency would translate into longer range, changing a key cruiser and warship design trade-off. This is a broad counterfactual effect rather than a quantified redesign.