Flash clock time separators 
When enabled, the clock indicator (which by default is the colon) will flash on and off each second.
- Tested on macOS: - Ventura
- Monterey
- Big Sur
- Catalina
- Mojave
 
- Parameter type: bool
Set to false (default value) 
The time separator stays solid continuously.
bash
defaults write com.apple.menuextra.clock "FlashDateSeparators" -bool "false" && killall SystemUIServerSet to true 
The time separator flashes every second.
bash
defaults write com.apple.menuextra.clock "FlashDateSeparators" -bool "true" && killall SystemUIServerRead current value 
bash
defaults read com.apple.menuextra.clock "FlashDateSeparators"Reset to default value 
bash
defaults delete com.apple.menuextra.clock "FlashDateSeparators" && killall SystemUIServerSet value from UI 
- Access Clock settings from macOS UI
- Toggle "Flash the time separator" value