protected function isApplicablePage(array $notice): bool
    {
        $notice = $this->normalize($notice);

        if ($notice['for_page'] && $notice['for_page'][0] === '/') {
            // If it begins with a `/`, treat it as pure regex like `isMenuPage()` does.
            $applicable_pages = [$notice['for_page']]; // Delimiters not supported here.
        } else { // May contain WRegx, but `|` is not a reserved char, so this is OK.
            $applicable_pages = preg_split('/[|\s]+/u', $notice['for_page'], -1, PREG_SPLIT_NO_EMPTY);
            // e.g., `index.php|post.php`, `page-slug{-*,} || another-page-slug`, or `slug1{-*,} slug2`.
        }
        if ($notice['not_for_page'] && $notice['not_for_page'][0] === '/') {
            // If it begins with a `/`, treat it as pure regex like `isMenuPage()` does.
            $not_applicable_pages = [$notice['not_for_page']]; // Delimiters not supported here.
        } else { // May contain WRegx, but `|` is not a reserved char, so this is OK.
            $not_applicable_pages = preg_split('/[|\s]+/u', $notice['not_for_page'], -1, PREG_SPLIT_NO_EMPTY);
            // e.g., `index.php|post.php`, `page-slug{-*,} || another-page-slug`, or `slug1{-*,} slug2`.
        }
        foreach ($applicable_pages as $_applicable_page) {
            if ($this->s::isMenuPage($_applicable_page)) {
                $is_an_applicable_page = true;
                break; // Have what's needed here.
            } // In short, if any match current page.
        } // unset($_applicable_page); // Housekeeping.

        if ($applicable_pages && empty($is_an_applicable_page)) {
            return false; // Not an applicable page.
        }
        foreach ($not_applicable_pages as $_not_applicable_page) {
            if ($this->s::isMenuPage($_not_applicable_page)) {
                return false; // Not applicable.
            } // In short, if any match current page.
        } // unset($_not_applicable_page); // Housekeeping.

        return true; // Applicable page (default behavior).
    }