Certainly a contributing factor to the erratic schedule was Dick Clark's multitude of his media empire's obligations. At the time, I believed what I heard, that the salute-and-exit signoff was so that he could dash over to the American Bandstand set, which clearly wasn't the case. But, in a figurative sense it was. One of the things that fascinated me was that he scheduled appointments in tenths of an hour, rather than by the quarter hour, so you knew to conduct business fast when you were scheduled at 2:18. It certainly helped the odd studio scheduling arrangement that the host had extraordinary time management skills, and I'll bet Mr. Stewart saved a lot of money in the process.
Occasionally at work, I've tried to do that by calling a "12-minute meeting." Then I use up any time I would have gained by explaining to everyone who asks "why 12?"