In a speach I gave at last month's 4th Tianjin International Conference on Software Testing: I mentioned an article about how much Google CEO Larry Page cares about CI: he gets a build (I would think, build status) on his phone each day. The audience were very impressed, I was the same when I first saw it. Although I had no doubt about the importance of CI myself, any projects who had done successful CI with automated testing would agree that, certainly the teams I helped with their CI process would agree with me. What impressed me was finally top management of a global leading firm acknowledged this.
Before I dump my thoughts on this, here is the article from Fortune:
Page told audience in Europe that he gets "a new build" on his Android phone each day. "It continues to work better and better every day."
I highlighed two words in Larry's sentence: "Continue" and "Build", which is CI. And he used 'work better and better every day', which is the outcome of a successful CI. What Larry did not say (or maybe didn't want tell the competitors) was use of automated testing, which it is not hard to figure out. You wouldn't just compile the code, and tell your CEO that 'we got a build'. Would you dare tell your CEO each new build is getting better without comprehensive testing?
To get a build 'each day', manual testing is certainly not a workable approach, got to be automated testing. Some may naively say Google has money, they can hire many manual testers. No, more manual testers won't help, humans just can't do regression testing again and again without (lots of) human errors.