Presumably this is born out by results in sports shooting competitions? Cite anybody?
Of course there are situations where people’s lives are in immediate danger.
But you ignore e.g. hostage situations, where negotiations can lead to disarmament without anyone firing.
Incidentally there are cultural differences between the US and the UK (both fine countries) and this is one of the biggest.
Many US posters (and all US police) own a gun and have had training.
Most people in the UK (and most police) have never owned a gun and never fired one (even in training).