Once came across a group of about 10 riders and their instructor at the start of a well known Scottish trail center red descent. They were all stood there blocking the trail while the instructor talked about the first feature. They all looked at us, including the instructor then went back to their discussion without moving. After, very politely saying "can we get through please?" they moved!
Day 1 Trail Center Instructor School First Lesson:
When stopped for the purpose of demonstration, discussion, technical problem or accident. Firstly ensure the group safety, with all people and equipment removed to the side of the trail. Then be careful not to block or hinder other trail users who may be riding at speed.