The tool tip for the sovereign weakness Inefficient is misleading to how the penalty is applied. The tool tip says, "Constructing Improvements take 25% longer".
This wording seems to be an empire wide penalty. What happens now is that the penalty is only applied when the sovereign is in a specific city. When in the wilderness, their is no production penalty applied to construction times.
Either the Inefficient penalty is not working as intended, or the tool tip need to state that the penalty happens when stationed inside a city.
