> Don't you get dinged as a slow performer?

No because the document is not the work. Management wants someone to figure out the solution to their problems. The document is just a step in solutioning.

Without the doc, others would have to re-do all that work if you get hit by a bus. Or you’d be stuck in endless meetings conveying the vision instead of figuring out the next problem.

Document length is inversely proportional to the quality of your thinking/insight. When you create fluff, everyone can see you didn’t do the work.