Creating a list of tickets that have not had an agent reply in over 24 hours is a good tracking tool.
To generate this list, a report can be created using the DPQL format below:
SELECT tickets.id, tickets.subject, tickets.agent, tickets.status
WHERE tickets.date_last_agent_reply < (NOW() - INTERVAL 24 HOUR) AND tickets.status = 'awaiting_agent'
The resulting table should look like this: