[rjzzleep]

I guess all the people commenting are much more competent than the people I've worked with.

Even with tests, I've seen startups do double charges on accounts and whatnot on deployments which didn't show up until the next day. I've also seen ops people updating OES where the storage service would segfault a day later. How does DevOps and OES go together in one sentence, you ask? it doesn't, but it just means not all ops people are pure wisdom either. The guy caused others to waste 72 hours of compute resources, because of this. So it's not limited to Dev. And yes, the first company did learn from the double spending bug, but why learn on a saturday?

So even if your DevOps practices are amazing and you have 70% test coverage on all your components, that doesn't mean you can't deploy faulty components where the deployment itself appears successful. Now what? Things aren't failing, they appear just fine. Someone has to go in and debug the problem, it may affect multiple components, it may be critical, and a simple rollback may not cut it.

Friday deployments are fine for certain components, but surely not as a general rule for everything? Friday deployments are like Monday morning or Friday meetings. You can do them, and most of the times they'll be fine, but maybe out of respect for your colleagues you shouldn't anyway.