I think it depends on your definition of self-promotion. To me, performing and excelling at your job should be sufficient to make you visible. In a flat struct

I think it depends on your definition of self-promotion. To me, performing and excelling at your job should be sufficient to make you visible. In a flat structure you're known as the responsibile party for project X, therefore, the self-promotion is happening automatically, as opposed to a deeply nested structure where your department's name is linked to the success of project X, and within the department your team takes the credit, and to be visible you'll have to actively self-promote.