When I look at the tools already available under Statistics | General | Cache Stats, I see things like "Geocache types per area", "Geocache sizes per area", "FP per area", and "FP per D/T", but there is no such tool as "D/T per area".
I want to propose a new tool to visualize the number of complete D/T grids available in a specific area (country/region/county, depending on user's choice). It should be based not on finds of a particular user but on all active geocaches in that area. As a possible implementation, it could show a map in which regions are colored according to the maximal number of D/T matrices per country/region/county and showing the rarest D/T combinations for every country/region/county.
The practical use for such a tool would be, for example, to convince reviewers that enough caches exist in a given region to justify a D/T-matrix based challenge. If I want to publish a challenge to complete the D/T-matrix in a single county, seeing how many caches are available there for every D/T combination is currently impossible with the available tools. If this is implemented, one could also see in which regions a D/T matrix is possible to complete at all, and which specific combinations are missing.
At the moment I can do this for countries and regions by creating a Location filter in c:geo, but that works only for single D/T combinations, requiring a lot of manual work. It also doesn't work at all for counties because county is not included in the location field in c:geo.