Wondering how often the widgets update in the background?

The widget usually updates itself once you close the main app.
If you don't open the app, all widgets will be updated at least once every hour.
The “Today Widgets” are updated in the background every 15 minutes, therefore, the data it contains is 100% up-to-date.
The Lock Screen Widget updates every 10 minutes. It may vary a bit, depends on what the OS allows.