The National Fire Protection Association (NFPA) requires that every building or structure be designed, constructed, and maintained to protect occupants who are not intimate with the initial fire development for the time needed to evacuate, relocate, or defend in place.
According to the NFPA, a successful layered fire protection plan should be designed so that reliance for safety to life does not depend solely on any single safeguard. Additional safeguards shall be provided for life safety in case any single safeguard is ineffective due to inappropriate human actions or system failure.
Similar to NFPA, the International Building Code and International Fire Code both provide a system of protection schemes so as not to rely on a single safeguard to protect building occupants.
*Source: NFPA, Fire Loss in the United States During 2018, Ben Evarts