<prompt> Translate the following text to EnglishWanafunzi wa Marekani waliandika katika makala hii kwamba post inaweza kuruhusu gharama zake za utoaji kwa kupunguza mzunguko wa huduma kwenye njia zisizo na faida hadi hatua ambapo zinakuwa faida.  <response>: It has been pointed out by the American co-authors of this paper that a post could rationalize its delivery costs by reducing the frequency of service on unprofitable routes to the point where they become profitable Cohen et al. 