So I am in Germany and this is what I know about the "Metropolitan witnessing", I did it once.
Each person had to attend a three hour instruction session.
Here is what I can remember.
Some time was spent explaining how the publisher should react if approached by the police or some other authoritative figure, what the laws are regarding this type of work and other relevant legislative problems that could occur when doing this type of work.
Where and when the carts are to be picked up and brought back and the shift changeover.
Where to stand and where not to stand with the carts, and basically in Germany they cannot be in one location for more than 15 mins. so they are always on the move.
How to react if anybody acts aggressively towards them, one of the things that was stressed was not protect the carts or the literature if anybody deliberately tries to do damage, but to call the police. Any incident should also be reported back to the elders.
Another thing is that they are not to try and engage anybody in conversation, this is something that many here have commented on, but they really are instructed not to do so. Exception being when they are approached, then they can have a conversation.
But the time I did do this, I though what an absolute waste of time.