Depois de escrever minha pergunta, mas antes de postar, fiz uma pesquisa no Google por [ norton family warn before time restrictions ]. Descobri que o artigo da "Família Norton" da Wikipédia contém a resposta à minha pergunta:
Parents can define a range of hours when children are blocked, with separate settings for each child, weekdays and weekends. A daily time quota can be configured as well. Children receive a warning 15 minutes prior before blocks begin or a time limit is exceeded. The amount of time left can be checked via the Norton Family system tray icon. In the last minute before forced logout, children can postpone it by pressing a button, disabling the desktop and leaving only the Norton Family icon functional. Parents can then enter their credentials to grant a time extension. The time-management feature can also warn children, rather than cutting off access. Exceeding limits will result in a log entry. Time limits are enforced across multiple PCs. Changing the system time does not affect Online Family. The activity will be logged, however.
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