Everything you build should be both automated and repeatable
Why?
What if your infrastructure breaks? What if there is a disaster? Rebuilding can take considerable time. If your solution is built from repeatable code then recovery can also be automated.
Chunks of well crafted repeatable code can be pieced together to form more complex solutions, saving time in the long run.
Continuous Deployment which is a pillar of agile entities can only be achieved with automation.
A complete and well defined automated solution creates a perfect staging environment, protecting your production environment without the need for human change control.