Quite true. I advised convoying of supplies to Malta because I assumed that you, like me, would want to build up a large invasion force in the area prior to your first landing. I usually convoy over the actual invasion force, plus a small horde of infantry (generally everything I have uncommitted) for use in expanding my beachhead immediately after the invasion during that period of vulnerability when the AI is trying to redeploy forces from elsewhere to contain my landing.
As soon as the landing succeeds my assault fleet goes back to Malta, picks up a wave of reinforcements, and then rushes them back to the beachhead to offload. Meanwhile the forces which made the landing are already on their approach march to attack another province inland from the beachhead. By the time they reach and are attacking that prov, I am already bringing in another group of reinforcements from Malta and the first reinforcement group is on its own approach march to one of the coastal provinces bordering the initial landing spot. In this way I very quickly pour in all of the forces I have in-theater for the invasion, expanding the breech both inward and laterally along the coast, and the AI has no chance at all of ever establishing a static front line to contain me. In no more time that it takes to drive from Marseilles to Vichy, Vichy France is being annexed by France and my forces are now on Allied-owned territory and no longer calculating their logistics penalty from Malta.
