Yeah, that's a pithy truism that gets thrown around anytime someone wants to make the argument to not try again.

In this context, I'm not so sure about that. Erusea's constant invasions of its neighbours, despite variables changing (the introduction of autonomous drones, the takeover of Stonehenge, so on), all fail because of the repeated refusal to acknowledge the fundamental issues there were every time - the nations of Usea did not want to be occupied, and the nations of the other continents had an interest in supporting them through organisations like ISAF and the IUN. Invading over and over again despite this, therefore, is not an adequate and normal approach for Erusea.