In Outlook, you can set your task working hours per day and per week. In Outlook 2016 and above, the task working hours has been set as 8 hours per day and 40 hours per week. You can change to different numbers with the steps below:
Step 1: Click the "File" tab from the Ribbon;
Step 2: Click "Options" from the left navigation pane;
Step 3: Click "Tasks" from the "Outlook Options" window;
Step 4: Type task working hours per day and per week in the boxes;
Step 5: Click "OK" at the bottom to close the "Outlook Options" window.