Object manager or manage each object separately

I have this situation where I have prefab that are projectiles which paint the terrain below them. My question is whether i should use a central "manager" that manages the objects in an Array or should I just put the code to paint the terrain in the script attached to each prefab?

My question for this is regarding performance as making a manager means more code as i have to manage an Array of the prefabs and when i instantiate a new projectile i also have to add it to the array in the object manager.