I have heard many times that since the temperture is consistent in the modern houses that we live in, that it is not necessary to check mezuzos twice every seven years. I asked Reb Avraham Tzvi Wosner if there is any truth to this and he told me it is not true. He explained that there were plenty of places that the Jewish people lived in the past that had mild climates and we don’t find rabbinic sources that say that they didn’t need to check their mezuzos because of the mild climate. It also is not true that houses had only a front door and no inside rooms. There are many indications that people had houses with multiple rooms throughout history.