For many continuous integration is still a dream. It is a proven that practice like building and testing the code continuously helps to improve the ROI in the long run.
What about Continuous Deployment ? How many times a can you deploy ? Even though setting up build and continuous integration is one time effort, it is the discipline that makes the build and continuous integration process to work. If you want to learn about such a disciplined system, read how the continuous deployment is done fifty times a day at IMVU from here