I would argue that DDD is not as efficient if your optimizing for speed and efficiency.

The problem is that there is now another variable you would need to keep track of: your UML diagrams / documents.

I guess creativity comes into play. For example if I am designing a video editing API. I could think bottom up and start from frames/buffers maybe. I might reason that I require a:

- Renderer - Singleton that is an editor which holds our sequences - Interfaces that can be exchanged for different types of editors - etc.

However the other approach is top down. Imagine how the ideal api looks like and go from there:

editor.addSequence(sequence) editor.process(item: [ .transaction(action: editAction), .transaction(action: saveAction), .transaction(action: finishAction) ]

^ so for example I might start from there and build the system from that point of view.

Anyways would appreciate more of a discussion here.