c4 Remote On Duration

Nikon D5100 custom setting menu c4 remote on durationExplanation: This menu defines after how much time of inactivity the receiver for signals from a remote control will be switched off – 1, 5, 10 or 15 minutes after activating it with the release mode in the shooting information.

Recommendation: The only reason to use the shortest period of 1 minute as a default is to save battery power.
Better increase the standby time and have it a bit too long than missing a picture.