Staff and volunteers arrive on the day with no time to spare. Here is the short version of the job, and the card you leave behind at the counter.
However long you planned to spend training the people behind each counter, the time you actually get is the gap between the staff briefing and the doors opening. Some have worked the venue before, some are volunteers who signed up last week, and all of them want one answer: what do I do when a guest is standing in front of me. The useful response is not a tour of the system but the shortest honest description of their job, given once at the counter they will be standing at, with a real ticket in their hand.
The job is small by design. The guest orders from one menu somewhere else, pays there, and the order arrives as paper at the counter that owes the items. Nobody at the counter has to decide what is on the menu, what it costs, whether an item belongs to them, or how the money is handled. All of that was settled before they arrived. What is left is read the ticket, make what it says, call the name, hand it over.
Say all five at the counter, on a test ticket printed before doors. Ten seconds of holding one answers the questions an explanation only creates: how big it is, where the name sits, how a note reads. Let them call the name off it and hand an imaginary item to you. People remember the shape of a thing they have held, and where the paper comes out is different at every counter.
Whatever you say in the briefing will be half-remembered by the second hour, so write the short version on a card and tape it where the person at the counter will see it without looking for it. Keep it to the things that stop work: how to change the roll, with a spare kept in sight rather than in an office, and the name and number of the one person to tell when printing stops.
When service is over, ask each counter the same two questions: what did guests keep asking you, and what did you have to guess at. The first tells you what the menu or the ticket is failing to say, and that is usually a wording change, not a training change. The second tells you which part of your ten minutes did not land, and you fix that by changing the five things you say, not by talking for longer next time. Written down after each event, that list gets shorter and a briefing that was barely enough becomes enough.