I made the widjet with countdown to midnight.
But widjet's seconds displaying incorrectly - always freezing (like work without updating)
Please check the very first KWGT FAQ
Can Kustom Widget update every second?
Android Widgets do not know if they are currently displayed or not, this means that they will run also when you are using another app like a browser (even if Kustom widget never updates when screen is off it still doesn't know if you are actually looking at it or not when screen is on), so, from a technical point of view KWGT could update every second but the feature has been disabled to avoid battery issues or performance issues when very complex presets are being used. This could change in the future if Android OS or Launchers will add a better support for this