I think doing EOLs on a trial lesson is probably one of the best things for the prospective trainee to do , my reasons are the following;
1. Most peoples perception of a helicopter is that if the engine stops you are going to die, very important to remove that myth, in a controlled manner.
2. If they are looking at going the whole way (reason for a doing a trial lesson) Then they should be shown what to expect during the syllabus.