I got an answer from Bully Pulpit, for anyone interested.
Essentially, although a mission only *requires* a single Wayfind and a single Attack Run roll, it is permissible to make extras. While this is usually too risky to do on a live mission, it is a good idea in training.
(This still seems dangerous to me; the consequences of failure are just as bad mechanically in training as they are on a live mission, AFAICT, so there's still a strong incentive not to roll. But maybe that's the point!)