Well in the recent Iran war they kept their major ships far from Iran and didn't try to do any major operations in the area where small Iranian boats like those used in the wargame would be a threat. Indeed none of the vulnerabilities exposed by the Millennium Challenge were actual issues in the recent conflict. Whether that means the lesson was learned or the red team tactics were exploiting issues specific to the wargame is not clear.
They have sang lalalala with their fingers in their ears instead of noting the lesson, and it still would have been a monumental waste to not reset and continue the exercise.