Which details matter most in a personal data guide?

A personal-data guide should connect information categories to collection purposes, recipients, retention, inferences, and available choices. It should also identify what is unknown. A list of categories alone cannot explain how the information affects someone. Which connections would you like to see illustrated?

I'd like an example that follows one piece of information from collection through sharing and deletion.

Retention is the part I find hardest to picture. I'd like to understand what happens after I stop using an app.

Showing where the explanation runs out of evidence would help me tell which questions still need an answer.