[Suicide Junkie]

I like it!

If you rounded off instead of rounding up, then you could have a restriction of no spaceyards on tiny worlds.

Perhaps it should be based on atmosphere; for airless worlds, spaceships would have a natural environment on the surface, and could take off easily. So, vaccuum worlds could have more spaceyards than other atmospheres, which could be limited to one...

Separately, what if ships can only be built at space stations, but bases can be built from planetary spaceyards.

SO, you need a space yard to get the base, which builds the ships in orbit.