You know looking back on these past episodes there were so many things that could have been done to avoid these deaths.
Shaun could have been saved if Kenny had helped Lee.
If Lee had been more attentive with Mark or if he had someone watch him in the St. John's house then he wouldn't have had his legs amputated.
Larry could have been saved if Kenny waited a bit longer, you actually see him take a breath. As a result it drives Lily to the deep end, and not thinking clearly murders Carley or Doug in cold blood. Heck, Lee investigating the missing supplies fed on Lily's paranoia.
If Ben had been honest with the group, Carley/doug, Katjaa, and duck wouldn't have had to die.
I know that we weren't really a choice with certain scenarios, but it's kind of sad to see how the smallest and most minute details can slowly build up and eventually produce heavy and dire consequences. Almost like a butterfly effect