The following statement came from some supplied NFPA information. Is it still currently in a published NFPA document?
Life safety from fire in residential occupancies is based primarily
on early notification to occupants of the need to escape, followed by
the appropriate egress actions by those occupants.
Fire warning systems for dwelling units are capable of protecting about half
of the occupants in potentially fatal fires. Victims are often intimate with
the fire, too old or young, or physically or mentally impaired such that they
cannot escape even when warned early enough that escape should be possible.
For these people, other strategies such as protection-in-place or assisted
escape or rescue are necessary.