Board Thread:Editor Board/@comment-26391060-20131028034630/@comment-1173941-20131029035005

They probably cleared the 50th floor on time... But think about the time it takes to recover after that. Even if 51st floor was not particularly difficult, it's likely there was delay, before clearing that floor.

Same as the 25th floor, which resulted in catastrophe, and forced the main clearing guild to stop.