Right...but it doesn't say that they can only start with 50% of available slides. IOW...if they indicate at the beginning of the drill that 2 slides should not be deployed, that still leaves 8. If 3 of those failed, they would still meet the 50% requirement.
Can anyone please tell me why the last mini failed? Was it that they did not get all the slides out in 15 seconds are defective slides (again and again) or something else.