Yes, family investment is a great tool to boost the production of a depressed region. You can use it to bounce back after an episode of looting for example. However, if your production had been closer to 100% in the first place, you would not have gotten much more than a break-even.
The more germaine difference is the size of the investment.
I bet that investment was in a
city. City investments maybe have a different payoff level than others?
