yep.
Definitely the organization and knowledge are the two most important pieces of SM work... I would say that the third, which is usually a result of these two pieces, is a calm demeanor. A lot of the time, the cast and director (not to mention other production staff members) will depend on you as the SM to reassure them when the going gets tough. Even if you are stressed and exhausted yourself, appearing calm and projecting an "everything is fine" attitude will make the whole process easier on everyone.