In documentation https://confluence.atlassian.com/confcloud/add-or-remove-page-restrictions-724764891.html text says "if a parent page has restrictions on it, each of its child pages will too. " . It works for children if restriction for parent is "all can't view, some people can view and edit". But if parent has "all can view, some people can view and edit" - children will not have that restrictions.
