Considering the fact that they've occupied Lebanon since the 80's, I'd say they've had plenty of time. They didn't seem to have crushed the spirit of the Lebanese people though.
The US doesn't intend to rule Iraq. It only wants the government there to treat all its people the same, and not export terrorism throughout the world.
Let us hope we leave from Iraq in as good a shape as the Syrians have left Lebanon in....a functioning republic with some mild violent elements but not enough to threaten most everyday activities.