[0.18.22] Map Gen Settings: Setting values for ore frequency below 1/6th seem not have any effect

[Impatient]

I started a new game and set the ore frequency to the lowest level (sliders all to the left).
In the game I wanted even lower frequencies and used Bilka's mod "Change Map Settings" to change the values.
The initial values showed in the mod's UI as 0.1666667, which is 1/6th, if my math is correct.
I changed them to 0.05 and expected to get like 1/3rd of the resource patches I currently had.
I used mod "Delete Empty Chunks" and then revealed 1000 tiles around my position with aconsole command.
Everything was like before. Like with 1/6th.
I experimented a bit with the values.
Changing ore frequency to higher values, eg 0.2 (1/5th) immediately shows effects.
But everything below 1/6th seems not to have any effect at all. Also tested extrem values like 1/1000th.

I wrote to Bilka on the mod portal ( https://mods.factorio.com/mod/ChangeMap ... 000b36f9fd , it seems this thread on the mod portal was deleted) who says the base game ore generation "works how it works" and that it is nothing the mod can do anything about.

I had a look at the mod to find the API code it uses ( surface.map_gen_settings ) and looked up the API-doc for it:
https://lua-api.factorio.com/latest/Con ... enSettings
https://lua-api.factorio.com/latest/Con ... MapGenSize

It says the value has to be "A floating point number specifying an amount."
That is all. No limits. A value of 0.05 should work then, i guess.

Now my question is, if someone can explain this to me. Am I doing something wrong, does the map gen algorithm work in special ways, etc ... ?

Has someone in depth knowledge about this and can shine some light on this for me?

Thanks!