from www.thoughtworks.com/insights/blog/case-continuous-delivery by @jezhumble (emphasis mine)

many of us are aware of the wide adoption of continuous delivery within companies that treat software development as a strategic capability that provides competitive advantage. [Amazon, Facebook, Google]
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Still, many managers and executives remain unconvinced as to the benefits

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Continuous delivery is a set of principles and practices to reduce the cost, time, and risk of delivering incremental changes to users.

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high performing organizations ship code 30 times faster (and complete these deployments 8,000 times faster), have 50% fewer failed deployments, and restore service 12 times faster than their peers.

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Implementing CD has second-order effects that reduce the costs of software development

For me, perhaps the most interesting effect of continuous delivery is the cost reductions it brings about by reducing the amount of time spent on non-value add activities such as integration and deployment. In continuous delivery, we perform the activities that usually follow “dev complete”, such as integration, testing and deployment (at least to test environments) — continuously, throughout the development process.

By doing this, we completely remove the integration and testing phases that typically follow development. This is achieved through automation of the build, deploy, test and release process, which reduces the cost of performing these activities, allowing us to perform them on demand rather than on a scheduled interval. This, in turn, enables effective collaboration between developers, testers, and systems administrators.

This change in process has extremely powerful second-order effects on the economics of the software development process.

my note:

a big part of this is due to reduced delay in the lifetime of a work item, since increased lead/cycle time for work will lead to increased amount of work for the same output, for a variety of reasons.