When you first create a project you will be asked to set the Progress Tracking Mode:


Summary of options:

Time Logs	Progress
Yes	Time Remaining	*Most commonly used configuration* Hydra will use the effort remaining of the task to automatically calculate the progress %. When a time log is entered OR the time remaining value is updated the progress % will automatically be recalculated.
No	Percentage Completed	Project / Tasks are not visible in My Timesheets and the Project Timesheets tab is not visible because Time Logs are not being used.   The Task Progress % is manually updated - for the purpose of costs / rates this will equate to time e.g. a 10hr task with 50% progress will count 5 hrs of effort towards costs / rates (if applicable).
Yes	Percentage Completed	Timesheets will be available but have no impact on the Task Progress %. You still have to update the progress % manually. This option is seldom used because you have to log time and update the progress as two separate actions.

Note:
1) If Time Logs are set to Yes
We recommend you avoid updating the Progress % via the Gantt
Users / Project Managers often forget the % and Time Logs are tied together.

Example - if you have a Task with an effort of 10 hrs and change the progress to 75%.
This will remove any existing time logs and replace them with a new single time log entry for 7h30m on the day the progress % was updated.

You can control this setting from Project > Admin > Preferences - Under Edition of Task Progress
You can also change this preference in the Blueprint's Template Project, to use this setting whenever a project using a Blueprint is created.

2) If Time Logs are set to No
This means timesheets are not being used.
The Project > Project Home > Timesheets tab will not exist.
Resources will not be able to see the project from My Space > My Timesheets.

You can update this setting from Project > Admin > Preferences - Under Tracking Type


Read More on setting the Default Tracking Mode options for your projects.