Will the zeds recalculate a new path if you have too many other zeds already occupying the initial path?It is not really the AI, but the pathing system, which scans the world and makes a layered grid around each player. All animals and zombies use that grid, but the grid does not know about them.
The path finding calculates the cost of every reachable grid node (block) as it works its way to the destination. Cheapest total cost wins. It will break through 40 blocks of concrete if that is the cheapest way to you.
It is the standard A* concept.
https://en.wikipedia.org/wiki/A*
Example:
You have 6 zeds.
They all path to the door since it has the lowest value.
3 zeds get to the door first.
Will the remaining 3 zeds recalculate a new path? say a block off to the right or left of the door?
To help spread them out.