Scheduling lunch is a great example. It's the kind of low-grade information which would be marginally beneficial to adversaries (who might arrange to, say, bug

Scheduling lunch is a great example. It's the kind of low-grade information which would be marginally beneficial to adversaries (who might arrange to, say, bug a restaurant if they knew VIPs would be meeting there), so it's worth hiding, but it's not really of public interest so doesn't need to be recorded durably. And the downside of leaking impending lunch plans to a journalist, one time, by accident, is likely inconsequential compared to, say, leaking impending military attack plans to a journalist, one time, by accident.