When you use checklists for service delivery, as I do, it's easy to slip into a routine. In fact, that's what checklists are designed to do: take best practices and make them a habit.
But nothing works every time. Doing the same training game at the same point in a given course may seem like a "best practice," but ignores the most important thing, which is the needs of the students in the class. People are different, and that means you can teach the same course dozens of times and no two deliveries will be exactly the same.
For example, there is one training game I usually play on the last day of a certain class. It nicely sums up the material in the class, and it's a lot of fun. Usually. But I know from experience that if the class is smaller than 6 or 7 people, that game isn't going to work. So I have to substitute something else.
Or, if the people in the class find games distracting and prefer a more straightforward presentation, I have to adapt my style to what will make them comfortable enough to be open to learning.
Checklists can be a wonderful tool to ensure a base level of service delivery, a "good" class. But it's going beyond the checklist to personalize the experience that makes a class not just good, but great.