That's dependent on how often you ship. Take your example of a load-based outage. In many applications there is a time-based peak (eg 11am-2pm daily for Facebo

That's dependent on how often you ship. Take your example of a load-based outage. In many applications there is a time-based peak (eg 11am-2pm daily for Facebook, or right before a concert sale opens for Ticketmaster) where load might cause an outage. In the worst case you might have a load-based outage per day. If you only deploy code once a week, then of course for you the majority of outages will be from load, and that's where you focus. OTOH Facebook pushes their entire front-facing code base twice (three times?) a day. They also twiddle thousands of A/B bucket test switches that turn code on and off, every day. After years of stomping on load-based outages, now their biggest danger is deployment.