You can:
...
• Define the number of yard duty breaks. See Defining yard duty breaks
(on page ).Anchor H_39662 H_39662
...
anchor
...
• Define the number of yard duties. See Defining yard duties
(on page ).Anchor H_39663 H_39663
...
anchor
...
• Change yard duty durations. See Changing yard duty durations
(on page ).Anchor H_39664 H_39664 
For a related video, see Defining the yard duty structure in Primary Time (#5086, 5.41 mins).