The answer depends a bit on the location of the embassy or mission abroad and the expected number of voters.
In large missions, where we know there will be a large number of Canadians voting—I'm thinking of western Europe, for example—we would normally send the ballots in batches. We'll count backwards from the date of the election to know the last day we can send a shipment via courier, but if we are expecting large numbers of ballots, we will send multiple shipments back to headquarters.
For missions in more distant locations—smaller missions or remote locations—we might not see the same volume, but we would go through the same process of working backwards from the election date to know how much time we need to allow for the courier company to deliver the ballots back to Canada in time.
