Shane's decision turned out to look correct because a critical and wild-card piece of information was missing.
If zombie Sophia was roaming the woods or still stuck in the marsh, it's reasonable to assume they would've found her and been done with the search long ago.
This is nonsense. It was a matter of whether or not she could reasonably be expected to be found alive, not whether or not she could be reasonably expected to be found at all. What is the point in finding her if she's a zombie? Closure? What is that worth?
And how much time as been lost and how many people have been put at risk in the meantime?As to how much time they spent there, I don't know. How long would it take for a little boy to recover from a gunshot wound with 6 pieces of shrapnel impeded in him under the care of a veterinarian?