> Yes, the average distance per run may be higher for the 5 companies, but it won't be 5x.

You contradict yourself at the end of the comment. Yes, it could be estimated a linear equation (mx + b) where m is the cost per house and b is the cost per route, roughly. And then you could have a system of which equations, where each row in the system’s matrix corresponds to an additional company.

The optimal result is probably not 1 company, but it’s probably not 1 company per house either