The point of working out with a trainer (or pretend trainer) is that someone is forcing/encouraging/coaching to push the trainee. That needs to be emphasized before the workout starts so she knows you aren't trying to be a jerk. After each set, you encourage her and tell her good job. The trainer sets the pace between sets. Too much rest makes the workout too easy. You can decrease the weight if you see that it is too hard and you can increase it if you see that it is too easy.no offense but if she's a beginner, she'll quit on the second day.
So for a beginner, that's why circuit training can be effective, you can move from machine to machine, change your weight resistance easily, and still get a burn without smashing her ego/spirit. If she walks away feeling that she accomplished something, that's good.