Eric Reis on Why Continuous Deployment?

Under continuous deployment, as soon as code is written, it’s on its way to production. That means we are often deploying just 1% of a feature – long before customers would want to see it. In fact, most of the work involved with a new feature is not the user-visible parts of the feature itself. Instead, it’s the millions of tiny touch points that integrate the feature with all the other features that were built before.

This seems to be the key to continuous deployment.  You can still make huge changes while working in small batches by flipping a bit when you are ready to deploy the UI changes.