Upgrade priorities
So I've been playing this game for a bit and I'm currently sanctuary level 18. Most of my buildings are between level 16 and level 17. I've always prioritized my resources and storage units first.
The question I have is, should I continue to upgrade everything to level 18 before going onto level 19? I know there's prerequisites, but what about the buildings outside of those? Is it a good practice to just take your time?