How much does a portfolio matter in hiring?

I had this thought on my way to work: how important is a portfolio in hiring decisions?

A CV tells you what someone has done. But I wonder how much it shows how they think. That’s especially true in consulting, business analysis and product, where a lot of the work is structuring problems, making decisions and dealing with ambiguity.

A portfolio might bridge that gap by showing how someone approaches a problem, not just what they delivered. At the same time, not everyone gets the chance to build one, and not every role expects it.

This site is my own answer to the question.