Assignees can easily update the status of their tasks, even if they don't have editor rights. This must be done every time a task is completed. It is also good practice to review and update completion ratios of ongoing tasks at the end of each day.
The completion ratios of tasks are indicated by small progress bars in the Tasks list.
Method 1: The Completion Slider
Assignees can easily set what percentage of their tasks are completed by clicking on the task and moving the completion slider horizontally. Moving it to 100% marks the task as completed and notifies the owner of the task.
Method 2: The Quick Complete Check Box
Assignees can also quickly mark their tasks as completed by clicking on the quick-complete checkbox on the Tasks list. This box is only available if the user is an assignee of the task.