value ranges for homeworlds are in some hint ingame
suitable = within ranges for generation mentioned ingame in hint
its not about precursors - i didnt find any nprs with generation on and 40% chance - strange with 10 SUITABLE planets, about that lot of planets with low cost - 3 planets within 0.0-0.5 range were in ONE system im lucky as hell, but not with npr generation
I don't understand what you mean by "ingame in hint". Do you mean you hover your mouse over something and you get a tooltip? If so, what are you hovering over? The reason I'm pushing on this is that I suspect you're confusing colonization cost with suitability for NPR generation, especially since you mention "3 planets within 0.0-0.5 range", which sounds a lot like colonization cost.
For the criteria for generating NPR, please see this post
viewtopic.php?f=1&t=1366&p=11404&hilit=oxygen+temperature#p11404 and the thread containing it.
If the criteria you're using to define "suitable" are the ones in the post, then I agree, it's weird. On the other hand, it's also weird that you would get so many of them after surveying so few systems.
Thanks,
John