At DOZ, we roll out new tasks every day. If a task matches your profile, you will be notified by email. It is first come, first served, so if a task matches several profiles, the expert to claim it fastest gets to work on the task.
There is absolutely no expectation for workload. You work on the tasks you want to do within the tasks' deadlines.
Note: If you are away for a few days and not available for work, you can turn your "Work Status" to Off. Learn more about "Work Status" here.