These four ultimate aims serve as “stretch goals” that enable the improvement of software development and delivery. Notably these are aims and directions, not destinations. In the spirit of continuous improvement, you always have room to improve and are never “done”. You are either continuously improving or regressing.
The world of technology is changing continuously. This means implementations, tools and technical practices vary almost infinitely. However, the overall goal of any practice or implementation in productivity engineering should be aligned with moving projects and teams in the direction of these aims.
1. Clear Continuous Feedback: Meaningful feedback about changes that are delivered quickly and continuously. A person can only safely move as fast as they can comprehend the impact their changes have on a system.
2. Great Interaction Experience: Frictionless interaction with tools, frameworks, and platforms that are used to create value. Friction really matters when trying to make people more productive. Developers and operators are people too, the better the experience they have; the more productive they become.
3. Low Change Failure Rate: Frequently make changes to the system without introducing new problems. Moving fast and breaking things causes a lot of customer pain and rework which is not efficient. 
4. Short Lead Times: Relatively short amount of time it takes to deploy a change or feature to production. The longer the lead time, the worse off your project will be. 
“Low Change Failure Rate” and “Short Lead Times” are examples of how effective DevOps and Productivity Engineering go hand in hand. The four key metrics come from the research of Dr. Nicole Forsgren, Jez Humble and Gene Kim in the “State of DevOps Report” which can be summarized here: https://www.infoq.com/news/2017/05/forsgren-devops-performance/