With Screen On mode enabled, the screen stays on during the prescribed time. This feature no longer works after the screen turns off and turns on again.
1) Swipe down on the watch face, tap the Screen On icon, set the Screen On time, and enable Screen On mode.
2) Swipe down on the watch face and tap the Screen On icon again to end Screen On mode ahead of time.
3) End Screen On mode early by covering the screen with your palm to turn off the screen.