Widgets automatically refresh every 5 - 15 minutes. Also, each widget refreshes independently. In other words, a widget is not affected by the refreshing rate of other widgets or even by the refreshing rate of the dashboard as a whole.
You can find more information and the exact refresh rate for each type of widget based on its integration in our handy guide here.
Dashboards, on the other hand, refresh as a whole automatically refresh every 12 hours.
This is to ensure the latest state (which includes fixes and enhancements we push from our backend) is displayed everywhere, including TV screens and share links, and for everyone accessing the dashboard, including mobile and view-only users.
To re-iterate, widgets and dashboards refresh independently and automatically.
Have you added new widgets, changed the background color, or tweaked the design/layout of your dashboard and find that the changes are not showing up on your TV or elsewhere? You need to perform a remote refresh!