Dashboard Design For A Web App [on hold]

I am doing some research on dashboard design and it seems like there's no specific answer out there regarding approaches or best practices.

Suppose that we're designing a dashboard for a web-based app.

What should be included/excluded in the dashboard? How many items or cards are enough? Should we include shortcut to another parts of the application on the dashboard, if not then why?

Waiting for your answers, thank you :D