I could be exploring all the mechanics that Fulgora and Gleba have to offer. I've researched both planets and have a spaceship ready to take me there in a couple minutes. But nooooo... I instead want to utilize the insane scale of everything on Vulcanus to build rail networks to bring my SPM to the moon!
First, I want red, green, blue, and purple science to get unlimited mining productivity! But yellow science for enhanced military power sounds nice for medium demolishers, behemoth biters, and the Gleba enemies... And since I already have yellow science, I can easily expand to space science... And wait, I also can make Metallurgic science as well!
What do you produce on vulcanus?
Apart from green belts, miners and foundries
Almost Everything
Foundries make all iron and copper intermediates. Coal liquefaction for all oil intermediates. Water from the acid. And everything else is easy when you have all of that.
Thing is, nauvis is only needed for uranium and eggs, you can make every thing else on any one of the first 3 planets.
I even make all science except planet specific ones on volcanus.
But I don't want to ship tons of shit to nauvis. So I make everything there, it's not expensive with foundries and electromagnetic plants. So getting free ore on vulcanus isn't even a big thing.
Only ship science to nauvis