You’re right, bucket errors are the result of entwining things. Dimensional decoupling is a way of reducing bucket errors. In my personal experience, once I used dimensional decoupling regularly, it became second nature and automatic. I think it’s important to have low-friction ways of reducing bucket errors.
And yes, the most valuable decouplings are ones where they aren’t identical but we think they are. But until we try to decouple them, we don’t know whether they are or not!
Which diagrams disagree?
The pattern is an application of dimensional decoupling—the dimensions are the in the headers of the diagrams.
Top left: sad and not happy.
Top right: sad and happy.
Bottom left: not happy and not sad.
Bottom right: happy and not sad.