Your 'build' must be adaptable. Rapid population growth requires quick expansion of housing, food production, and services. A sudden decline (due to disease or starvation) requires immediate crisis management: reallocating workers, prioritizing essential resources, and potentially building new housing to encourage births once the crisis passes.
Monitor your population trends closely. If you see a large number of children, plan for future schools and workplaces. If you have many elders, ensure your food and healthcare systems can support them. Flexibility in your town's design and your worker assignments is paramount for long-term survival and prosperity.