At Uber, we support thousands of developers contributing to Android code. If builds are rapid, and stable, developer productivity is high. You’re working on a new mobile feature. It’s taken you weeks. You’ve been running your tests on CI. Your manager is asking you if you’ll hit the deadline. You feel confident, so you say yes. The day comes when you need to land your code. You try to merge it, but everyone’s merging code on the same day. Your code fails to merge, and your feature is delayed. Everyone is frustrated. We’ve all been there before.