Not every episode has to be on this story arc, sometimes it's good to have a a few stand alone episodes thrown in. As an example I would use The X-Files, they had their main story arc, but they also would throw in the odd episode every now and then, that was a simple stand alone episode that didn't further or have any connection to the main story arc. It would be nice every once in a while they would throw in just a good ol' fashioned zombie smashing episode with some thrilling heroics or funny or weird happening. I think it would be fun to have an episode where several characters, tell a story about the strangest/weirdest walker they came across. A simple stand alone episode on something going wrong during what should have been a routine collection run. An episode recounting what happened to a character(s) when the apocalypse first started or how some of the newer characters first met. Those type of stand alone episodes can be good to reconnect the viewers with what the liked about The Walking Dead in the first place.