It should be part of their training before they sign any route.
Route training is done with the trainee being provided with training maps and having to find information out on their own but doesn’t include information on other services or operators.
Presumably because it would need constantly updating every 6 months with timetable changes and operators not wanting to tell staff to wait for out of habit for non-existent trains (not in this scenario but avoids fresh trainees waiting for a train that’s cancelled or ten minutes late etc)