Using the "custom views" feature, it is possible to set up views to give you insight into which tickets have been unanswered the longest.  When completed, your ticketing UI will look like this:

Two new views have been added, to show you how many tickets have been waiting for a response for more than 1 day and more than 5 days.  This will help you avoid missing tickets and when combined with SLA policies, can improve the service you deliver.

To configure this setup, follow these steps:

1. Go to settings > Inbox Views

2. Select "Add New View"

3. Give your new View a name and description

4. This view should include any tickets that are waiting for a response.  That means "New" tickets, and those that are "Pending" meaning the customer is waiting for a response from us:

5. Finally, add the date constraint.  When a ticket is replied to, its' last updated stamp is incremented, so we can use this to limit our view to only tickets that have not been touched in the last day:

6. Click "Save" and enjoy your new SLA View!

7. Repeat the above steps, but instead enter "5 days ago" for the "updated more than" field.  Please note, the syntax for this filter must follow the pattern "n days ago" or "n hours ago".