Amr Elssamadisy ponders over pipelined Continuous Integration: "One of the well-known practices of Agile development is Continuous Integration, which entails team members integrating their code regularly into the baseline and running all unit and system tests. In most teams a CI server is used to do this quickly and automatically when code is checked into the baseline. This usually works well in the beginning of a project, but sometimes, when the team and/or code-base get large, the CI server starts to slow down. The cycle between builds grows and the feedback degrades -- a build may take an hour or more to respond with a pass/fail, and by that time several people may have checked in their code into an already broken build." (Is Pipelined Continous Integration a Good Idea?)

Nikita Ivanov also wonders about the Dark side of diligent unit testing.