Allow me to add point no .6 and 7. to that list of reasons why Juhan Shuttai! works in that sub stories are sprinkled throughout the series and make appearances even when their stories have finished. No. 7 is that as the characters take turns being the main protagonist in each episode, the seeds of their story such as Iokibe's have been planted earlier and when it come to their turn, I was already invested.
More than Kiseki no Hito, Juhan Shuttai! has become the feel good show for me this season. What Juhan Shuttai has done is the evolution of the GTO style formula. The eccentric main character does not magically solve people's problems for them and gives them a lecture but watches and maybe gives them to nudge to solve their own problems.
As an audience, it feels good to watch people succeed when we see the blood, sweat and tears (which is why the Bakuman movie didn't work for me) and Juhan Shuttai! is filled with such characters.
Like Kiseki no Hito, I'm very much on the fence of very watchable and must watch but what nudges Juhan Shuttai! over to must watch is that it subverted my all expectations and the episodes got better and better after a meh first two episodes. Must watch.