When evaluating the amount of bacteria in a habitat, why is the number of colonies a better indicator than the sie of the colonies?

Size of the colonies could depend on the size of the bacteria, not the amount of bacteria present in the colony, whereas the number of colonies is directly dependent on the amount of bacteria in a habitat. Another possible response could be that a population of bacteria that is divided over many colonies is potentially more resistant than a single colony, however the first response would most likely be more accurate.