This book was recommended in the The Phoenix Project. If you read that book, this is more of a formal structure to the concepts in that book. The importance of efficient, automated deployment pipeline can never be overstated. I’ve done software development in the pre- CI/CD era where just doing a build could take half an hour or half a day. Things that work magically now used to be so slow in the past.
If you need to provide value to the customer, you cannot be bogged down by a system that takes too long to set up, build, make changes and deploy. A lot of these can be streamlined and automated. If you have flaky tests that block your releases and if someone needs to baby-sit releases to make sure nothing goes wrong in production, you’re not operating as efficiently as you could. If you don’t have the necessary telemetry to debug production issues easily, you are probably spending way more time finding the root cause of issues.