Does the Events Countdown Widget picks automatically next event once the event has expired or user intervention is required each time the event has expired?
That is a setting you choose in the Type dropdown for the widget. Here’s more information on all the available settings for the widget that cover that in more detail:
Type: Choose whether you want the widget to countdown to the next upcoming event or to a specific event. If you select the Next Event option, then the widget will automatically start counting down to the next scheduled event once the first one has been reached.