ok, this is embarrassing but....

[BooDro82]

so is it good practice to occupy all planets in a sector?

[VanderLegion]

Yah, the more planets you have the better, since it means more income. For the most part you only need outposts on most planets with harvesters bringing the resources back to your colonies. Definitely shouldn't need more than 1 colony per system (sector? whatever you wanna call the view with the star and planets visible), you shouldn't need a colony in every single system, but I have no idea yet how many colonies you want vs outposts etc.