They were small, but their number was a lot, so when strangling them with vines, he would bind a lot of them and thoroughly squeeze them to make sure that all the zombie rats were dead before targeting the others.
But for a bigger target, he didn't have a problem because it was easier to target the heads of those bigger zombie rats, and he could easily see if they were dead.
The bigger zombie rats would cause more trouble, so he focused on dealing with them first. Of course, he also didn't forget to clean up the zombies that were trying to cross the line that he had set before.
Afterwards, they continued killing zombie rats for another hour before they finally killed all the zombie rats that were surrounding them.
Of course, there might be those that were not thoroughly killed, but it was already left for others to deal with.
