Then why at the beginning of the time jump were survivors misdirecting a herd to save Magna? It's been theorized that the herds they were misdirecting ended up with the Whisperers, but that's not my point.
Aside from the basic patrols why not expand further out and try killing every zombie as opposed to misdirecting? In the 2 year plus time gap there surely had to be time to start venturing quite far out and start eliminating every threat.
they were already misdirecting that herd. they put it in Magnas path. a herd that size would have shredded anyone it went up against. from the way they talked they did it a few times before.
one of the few things i don't like about the time jump is we don't learn what all they are doing. Dante and ken ( i think) did venture out further than they were suppose to and look what happened.
i figured they didn't want that in case someone ended up in a rough spot or people got lost. that would be my guess. however. we won't know.