You know how in Notification Center, how you see a banner for awhile? You can customize how long that lasts. To do so, use defaults to write a bannerTime key into com.apple.notificationcenterui. They should be an integer that shows the number of seconds for the banner to display, For example, to set the banner to 10 seconds:
defaults write com.apple.notificationcenterui bannerTime 10
Or 2 seconds:
defaults write com.apple.notificationcenterui bannerTime 2
Once you set the time, log out and log back in (or reboot) for the change to take effect. Enjoy
