We all have a tendency to follow a leader. It is usually easier and safer that way, but you still need to be aware of your own situation. A tragic example of this occured on Washingtons Olympic Penninsula in the mid 1970's. An Air Force C-141 was inbound from the Pacific at the same time as a Navy A-6 was approaching NAS Whidby in Puget Sound. It was the middle of the night, and both were under the control of a single controller at Seattle Center. The controller directed the A-6 to descend to 5000 ft., but addressed it to the C-141. Sometime later the Navy pilot called Seattle for permission to descend. The controller gave permission and quickly called the 141. There was no responce. The plane hit a ridge in the NW corner of Olympic Nat'l. Park that was some 5200 feet high.
In the ICC accident reports there are numerous cases where the Engineer and/or Conductor made an error and the other crew members did not question it.