To efficiently mark all the schedule items within a phase as complete, locate the corresponding phase in the Process Tracker and click on the tracker's icon. This feature proves particularly helpful when importing a schedule template that includes one or multiple phases that have already been completed.

This will open the following slider:

To mark all items as complete, click on the "Mark all complete" button. A modal will appear, allowing you to select the completion date by clicking on the calendar icon. Finally, click "Confirm" to confirm the completion.

 Please note that you cannot choose a future date for completion; it must be a date prior to the current day.