[QUOTE=poltroon;8128646]
It’s a schooling show. Do what’s right for the horse and the student to have a good round.
I personally would want to trot the jump, and canter after, possibly cantering out of lines. I would not care about consistency (that you trot every jump) as much as I’d care that it was a smooth, pleasant round. Ideally one would have smooth transitions from canter back to trot whenever they were done, and ideally transitions would occur in such a way that the horse is not cantering corners on the wrong lead. IE: exactly what you’d want her to do at home in a lesson. 
If she just needs to trot for the lead change and would like to canter the actual jumps, I would consider that also. Whatever is best for developing confidence and competence for the horse and the rider is the right answer.[/QUOTE]
This is a really good point. If your friend is going for show miles vs. ribbons it doesn’t really matter what the judge is looking for and I’d suggest doing whatever feels most comfortable in the moment - which may be keeping the canter out of the line and to the next jump if the horse lands smoothly on the correct lead and it all feels good.
That said, in my experience nervous first timers usually like to have a plan and don’t want to fully rely on making decisions in the moment. From what you’ve written here, my proposed plan would be, “The official game plan is to trot in, canter out of the lines, get the smooth downward transition back to the trot before the corner and trot the next jump. If the canter feels good, though, don’t feel like you have to come back to the trot right away - you can keep cantering until you feel like you need to trot or to get a simple change.”
And honestly, even though it’s not about the ribbons, at this level the judge is often looking for the smoothest round overall, which may be accomplished with the more thoughtful (if less consistent) ride.
TL;DR anything goes, do whatever feels right in the moment.