Efficiency
A measure of whether the right amount of resources has been used by a practice, service, or activity. It is about "doing things right."
Impact
Inefficiency bleeds capital. Whether it's wasted clock cycles, idle servers, or manual toil, inefficiency reduces the margin available for innovation.
Weinto take
We constantly optimize for Flow Efficiency over Resource Efficiency. It is better to have a developer idle for 10 minutes (low resource efficiency) than to have code waiting for review for 2 days (low flow efficiency). We optimize the pipeline for speed of value delivery, not for keeping everyone 100% busy.