This depends entirely on your unique case. Factors such as the location of the building, how big or small it is, extra features such as a large garage, a basement, or a swimming pool are also included, as well as how much you want to cover, especially home contents and personal belongings. Another factor that adds to the coverage is whether you will be using the property personally or putting it up for rent.
Each case is unique and what the buyer needs will affect what is covered greatly. Only those aware of the location of the building and its surroundings will know just how much coverage is adequate.