Pretty much every call center every day. It's a numbers game between having enough agents to handle every call without the queue getting backed up, and having few enough agents that they aren't sitting around with nothing to do. This is called the Erlang C formula and there are a variety of calculators on the net if you want to play with it.

I currently work at a place that prioritizes employee utilization over process speed, so my team has a foreverqueue to ensure that time on task (TOT on my metrics dashboard) is maximized to its fullest. I'm just glad it is tickets and not phone calls.