If you ever have to defend yourself, it is most likely to be in or around structures. Fights in civilian and law enforcement contexts rarely happen in open fields -- they happen in homes, offices, restaurants, gas stations, etc. It is important we know how to clear rooms if we expect to be good defenders and protectors. One difficulty in all this is that much of the room clearing knowledge circulating is really about team clearing tactics. If an individual employs team clearing tactics (without a team present), they are likely over-penetrating constantly and are very easy to kill.