I wonder if Convincing John was always meant to appear in multiple episodes, or if he was originally intended to just appear once and became so popular that he was brought back a few times. Or if maybe a writer came up with more ways to use him.
I noticed that Convincign John's first two episodes have his name in the title. I thought this was strange for his first appearance, as he isn't really too major. He just had two major scenes, and was mentioned quite a bit in the first half. I wonder if the writers meant for him to be mysterious (perhaps only appearing when he's putting on a show). Interestingly, Gobo and Wembly were both frightened when they heard that Mokey was going to ask Convincing John for help, and Red told Mokey that Convincing John was a fraggle that nobody ever comes to see, but when he performs, the Fraggles don't seem to be very afraid of him being around.
I wonder if the orignal plan was to have him appear in one episode, appearing as little as possible, and then have him return and be revealed to be indecisive.