Germany helping Italy in the Med all depends on if you are looking to knock Russia out with a quick punch or throttle them slowly to death. If you’re taking the long game approach, a German fleet in the Med is worth every IPC. It creates an incredible headache for the Allied player who expects to dominate the Med early. Then it becomes an arms race, and guess who is closer to their supply lines?
And once the Med becomes an arms race, the Allied player often stops buying as much with the US in the Pacific… and Japan can wear down Russia from the back.
Just general thoughts - game by game will obviously be variable.