Well, there was a very brief period during the Alpha test when the DSS overlay map was an actual "heat map", with densities shown by various colors (red, blue, green, etc.).The statement of devs seems kinda "shallow" :-D
So I will be doing what Im doing already... "guess" :-D
But it didn't work properly, and people found it confusing, so in the end they went with a simple blue overlay.
I still have a link to the original issue where you can see the dev reply --> https://issues.frontierstore.net/issue-detail/32054
In any case it works well enough. I've made billions off exobiology, and so have many others. With a little experience finding the bio/geo features becomes easier.