Sure they can roam till all hrs but they have to be mentchlich. Once my younger ones are in bed by 9pm the noise volume drops way down...and we enforce it. If someone is loud they are told the next morning that was unacceptable and they woke/disturbed so and so.
Me? Minute my younger ones are in bed so am I.
My big ones can pop in till I turn out my light about 10.30. then they are on their own.