To limit the probability of the inadequate embedment of lath in stucco, which could lead to the deformation or cracking of stucco due to excessive shrinkage.
Where stucco is applied to masonry chimneys, this is to limit the probability of precipitation or meltwater ingress, which could lead to the premature failure of chimney liners, which could lead to the leakage of carbon monoxide gas into living space, which could lead to the acute poisoning or asphyxiation of persons.