There are two kinds of lessons you can learn when you mess up: 1. Be more careful next time so that you're less likely to make the same mistake again. 2. Fix

There are two kinds of lessons you can learn when you mess up: 1. Be more careful next time so that you're less likely to make the same mistake again. 2. Fix the system so that nobody can make that kind of mistake again. Learning lesson #1 will means that you're less likely to make the same, but learning lesson #2 will prevent you and your team from making that same mistake. For something that's as easy to test as "is the site working", the real lesson there is that you set up your deployment system so that the website needs to respond to a health check before the deploy finishes. (I realize this is nitpicking and isn't the point of the article, just thought I'd mention it :P)