The core principles of ALMA are
Sustainability. As long as a service is useful it should sustain. That means that everybody involved in the service needs to continuously improve its sustainability. This includes being sustainable environmentally, mechanically, economically, and humane in respecting the limits of people. This combats the disease of overburden (muri), which is a source of much waste but often disguised as value ("Come on, of course you can push it a little harder!").
Flow. Smooth out unevenness, batches, variations, waiting, where it can be done without breaking the first principle. Unnecessary variation that can be removed without making the service less valuable should be removed by clever inventions. Variation that is caused by the inherent variability in the human nature shouldn't be removed but handled, by clever inventions. This combats the disease of unevenness (mura).
Effectiveness. Do the right thing. Don't do the wrong thing or the useless thing. Don't try to make more of what is not the right thing. What is good enough for now and safe enough to try? Do that and proceed. This combats the disease of wasteful actions (muda). Remove waste, but not so that you introduce unnecessary unevenness or overburden.
These three principles will result in a truly efficient flow, but efficiency is not a core principle of ASLA. This is because when you aim for efficiency, you often fall in the trap of suboptimization by trying to maximize resource utilization in all parts of the flow. This causes overburden on people and tools, work waiting in queues which is a terrible waste, overproduction in parts of the flow which makes other parts of the flow instable, and in numerous other ways worsening the output while increasing the cost per item.
In order to sustain an effective flow, you need to build upon the foundation of the gemba, the floor, the place where value is created and waste is discovered and removed. The foundation is created as we saw in the section about the gemba from two other principles:
Transparency. Overburden, unevenness, and waste always hides. By making things visible, we enable action built upon empiricism (real data and true understanding), and so supports
Empowerment. It is the people who are doing the work that should decide on how the work is done. This means that they need to be enabled, not only by transparency, but also by given the tools and abilities to act in a fruitful way, and given the permission to do so.
So: try to improve the flow in a sustainable way by looking at the whole, work together with who you are and what you have got, stop doing what is not valuable, and respect the principle of the gemba: make everything transparent and empower people to act for the better upon what they see.