When you actually sit down to write some code, you learn things that you didn't get from thinking about them in modeling terms...there is a feedback process there that you can only really get at from executing some things and seeing what works
Martin FowlerContinuous Integration is a software development practice where members of a team integrate their work frequently, usually each person integrates at least daily - leading to multiple integrations per day. Each integration is verified by an automated build (including test) to detect integration errors as quickly as possible. Many teams find that this approach leads to significantly reduced integration problems and allows a team to develop cohesive software more rapidly.
Martin Fowler