Ash Maurya – 3 Rules for Building Features in a Lean Startup:

"While some learning happens during the requirements stage (driven by customer development activities), most of the learning happens only after we ship a release, with very little learning during development and QA.

Even though building a product is the purpose of a startup, product development actually gets in the way of learning about customers.

While we can’t eliminate development/QA or increase customer learning during those stages, we can shorten the cycle time from requirements to release so we get to the learning parts faster. That is exactly what Continuous Deployment does."