It really depends on the requirements of your workflow.
For example, you could require that only 'n' writers need to complete before moving on. Or, you could allow the approver to override the writers and allow them to explicitly move forward, even if the writers haven't completed yet.
The trick in both these cases is a feature of join called NoutOfM - this just means you can specify how many of the forks need to complete before the join progresses. So, you could specify '1' for your writers join which means that the first writer to complete will move the workflow forward to the approver.
If you want to allow the approver to override, then I would create a further fork that splits into the writers fork you have now on one side, and allocate an 'in progress' task to the approver on the other side. Set the join NoutOfM to 1. Provide an 'approve' transition for the approver on the 'in progress' task. Either the writers will complete first, or the approver (if they get inpatient).
