It took me 4-5 hours to read and understand first few chapters of Kubernetes in action, I annotated a lot text as notes on the Oreily site, but didn't have to go back to it. I didn't have to do any security and account management stuff, it was being done by someone else. After 3 years of working with plain Kubernetes and OpenShift, I still didn't have to go back to the book. Basic concepts in Kubernetes are easy to understand, if you're working as a developer to deploy your apps in it and not in DevOps managing it.
https://www.oreilly.com/library/view/kubernetes-in-action/97...