"Map overestimation," or "the contemporaneity problem," derives from the assumption that settlements identified during surface surveys were occupied throughout individual periods. Inductive and simulation analysis have been used to ascertain the degree of contemporaneity in surface survey data sets, as variation in settlement location is critical for understanding population density and demography, which inform social, economic and political interpretations. This paper revisits the inductive approach to interrogating survey data developed by W. M. Sumner and the simulation model approach developed by R. E. Dewar to explore the survey data from two regions within South Asia's Indus civilization. This analysis demonstrates the strengths and weaknesses of these approaches. It also highlights the variability in settlement systems in different areas within the Indus civilization and shows that consideration of stability and instability within settlement systems is an important factor when considering dynamics of resilience and sustainability.