When inside a crack, Michael only knew one way to open the exit: killing one-third of the original creatures within.
A third of the monsters is calculated from the moment someone first sets foot into the crack after the previous group has exited through the exit.
Without meeting this requirement, it was difficult for the average supernatural to leave.
According to some of the posts Michael had read on the forum about corrupted-type cracks, it wasn't uncommon for people to find themselves trapped without any way to escape. This was where the crack's Supervisor came into play.
The time allocated to supernaturals inside cracks wasn't just to manage the crack but also served as an indirect signal of when rescue would arrive if they were trapped.
While the people inside the crack couldn't leave without killing the required number of monsters, this limitation didn't apply to those outside.
