I definitely wouldn't argue with the fact that we have to think what we build, design carefully, etc. However imagine the world with massive test coverage that

I definitely wouldn't argue with the fact that we have to think what we build, design carefully, etc. However imagine the world with massive test coverage that provides instant regression testing and the world without it. What would you choose? We do have thorough peer reviews, that's what Phabricator is for and nothing gets in without passing a code review. Some more comments. 1. True, but you have to hit a combination of a test bug/feature bug to let the feature bug slip through 2. Also true. And we had to deal with those type of bugs. When the area is tricky (transaction log rotation, quorums, etc) we sometime have to the extends of proving things formally. 3. Very true. And scenario based testing will only get you this far. Receiving customer feedback is critical for that. Obviously SAS has advantage here. 4. Everything is a tradeoff. We definitely design/prototype hard features before we build them I think the right way to put it "Once you put yourself on the scale between chair legs and a space ship, you should choose how you run the engineering process".