Till/until all hours - Idioms by The Free Dictionary
till/until all hours
until all hours
Fig. until very late. Mary is out until all hours, night after night. If I'm up until all hours two nights in a row, I'm just exhausted.
till (or to) all hours till very late. informal
till/until ˈall hours until very late at night or early next morning: She sat up till all hours trying to finish her essay.