Each time remains of an ancient city are uncovered, I wonder the same thing: is the estimation of size of the city correct? They include all the settlement rema

Each time remains of an ancient city are uncovered, I wonder the same thing: is the estimation of size of the city correct? They include all the settlement remains. But perhaps it was serial - that is, new places were built as old ones decayed? They were often mud brick. Perhaps it wasn't 1000 people, but 100 moving 10 times etc.