Walking dead is the king of spreading 4 episodes of content across 12 episodes. You could watch the season opener, the 2 episodes that close the first half and start the second if each season, and the finale, and not miss anything of substance.
You've seen the best. I stopped somewhere in the middle of S3 because it was so bad. S1 was tolerable but honestly only the pilot was good. Kids watched all of it so I've got an idea how it went on; like a bad and cheap soap opera