CODAG propulsion for endurance and high-speed interception

Was the CODAG arrangement primarily intended for diesel endurance and turbine-powered sprint-and-hide tactics?

Yes; diesels favor endurance and turbines provide sprint power, though real operations need not follow that division rigidly.

Combined diesel-and-gas propulsion is described as broadly following this division: diesels provide endurance, while turbines supply power for high-speed interception and sprinting. Turbines were also used for some open-sea work, so the operating pattern was less rigid than the question suggests.