Do you know that there are some people out there that still believe the Blair Witch Project was real? That there really was a Blair Witch in Maryland that began this all?
The whole rumor was part of an Internet marketing gambit to stir up ticket sales, which obviously worked. But there WAS no Blair Witch story before the screenwriters invented it.
Yes, they did exhaust the actors, and frazzle them completely, but the actors knew this was part of the deal to bring out the realism.