From my vantage point watching the reruns starting in 1974, the Pollocks bludgeoned plot points till they were bleeding. The whole Mike in Asia was dragged out mercilessly. I am guessing that, early on, the powers that be realized that Michael Landrum was a huge casting mistake and they simply lengthened the story there while they were waiting for a better acting option to throw into the heavy duty business with Toni and Alan. They were also probably hamstrung with using him until his 13 week contractual cycle was up.