How does a courier company sort addresses ?

I was interested in knowing how a courier company works in deciding the addresses to be given to a certain delivery boy, in order to drop the parcels at those addresses.

So let us say that the company decides to give a delivery boy parcels belonging to a certain locality.

Now the question is whether they will provide these addresses to that boy in a haphazard order or in a logical order.

One way of giving in logical order is to list down those addresses in such a way that the consecutive addresses in the list are basically adjoining or proximate to each other.

This way the efficiency of the delivery boy would be improved, thus improving the metric of number of deliveries per day.

Else, if the addresses are given in a haphazard manner, then the delivery boy who does not know the geography of that locality very well may not travel through the addresses in an optimal way, thus travelling more distance/order than what is required.