How to improve efficiency in software engineering?

Activate the untapped human potential of your organization
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Effectiveness is the degree to which an intended outcome or objective is achieved
Efficiency in software engineering is about how well a team's skills and experience cover the knowledge required to achieve those outcomes.
Foster a culture where effectiveness and efficiency coexist, creating room for innovation and growth.
Ensure efficiency initiatives expand the organization's options, avoiding bureaucracy and structural rigidity.

There are several causal factors leading to low efficiency. A common trait to all factors is the presence of either underutilized or wasted human potential. Thus, they can be used as indicators for the presence of all factors. Hence, if you find instances of either underutilized or wasted human potential you can be sure at least one of the factors is present in your organization. All factors leading to low efficiency have the root cause of lack of managerial oversight.