Battery saving on many Android phones restricts background work, which is the most common reason widgets don't update on time. Letting Numable run in the background makes updates more reliable.
Background refresh also has Home-screen widget updates: Standard updates most often and uses the most battery; Balanced is the default and balances freshness and battery; Saver uses the least battery and suits a home screen with many widgets. On Free, widgets update at most once every 5 minutes.
If you use reminders, the same settings also help them arrive on time.