Such analysis may be useless for you, but not for Indian Railways.
Population of the town/city & its significance is one of the criteria to provide stoppages, and the same is applicable for introduction of trains as well.
Rather...
more... judging usefulness of the analysis, you may please go through the attached Railway Board letter, and understand the content of it.
Regarding stations serving other Non-Railhead towns, it remains same across all district(s).
Donakonda railway station serves Darsi & Podili
Repalle railway station serves Avanigadda & Nagayalanka
and there are many such examples across Indian Raiwlays. Nothing strange with Kurnool district, in specific (in this regard).
Public & DRUCC members from Nandyal had made numerous representations, to revise schedule of Guntur-Kacheguda-Guntur Express (which was a passenger earlier), in such a way to arrive Kacheguda early in the morning, and to depart from Kacheguda in the evening.
But such representations are not considered by concerned authorities, in view of resent from few public representative's at Kurnool, stating that it is the only overnight train connecting Capital Region (Guntur is also part of Capital region).
According to them, Guntur-Kacheguda-Guntur Express is serving as a train, connecting Kurnool with Amaravathi Capital Region (Guntur).
If not, you may please confirm, so that necessary representation will be made to concerned authorities, to revise schedule of Guntur-Kacheguda-Guntur Express, as requested by public of Nandyal.