Mastery is an exceptional level of proficiency which isn’t realistically achieved, let alone sustained, by most people. Competence and mastery are very different.
In the context of the application of my defensive carry weapon, I rank the demand for proficiency in various skills using the same risk assessment matrix as I would any other process: compounding probability with severity to determine a rankable risk profile, and then train and practice towards the highest compound scores first, and less so down the list.
Unfortunately, the severity of any defensive situation is gravely extreme, but our compounding attribute of frequency/likelihood/probability would prove training and practice for a controlled and rapid drawstroke to deliver fire at short range, within or just outside of arms reach is most pertinent.
The magnifying factor for an active shooter situation, in terms of severity, will vary from one individual to the next. As an example - for my wife, the gravest severity scalar is her death or that of our son. There’s no greater loss opportunity - we’ve discussed and determined, in an active shooter situation, her priorities are such she would only be willing to put herself at risk for our son, no others. As such, her prepared, planned, and practiced strategy only considers that consequence profile. “Run, hide, fight” is most pertinent for her, and is unwavering. My personal consequence profile is larger, as I rank a higher value on the survival of others than myself, so my interest to first secure my family, then act to prevent further loss of life would put me at greater risk, and also require greater demand upon the skills pertinent to the scenario. Firing draws fire - my wife won’t accept the risk of drawing fire to herself or my son, whereas a failure to stop on a long distance shot which draws fire towards me might mean less firing at someone else, which is a prepared, planned, and practiced strategy with an accepted risk of an unfavorable consequence.
Could my wife need to send a shot 75yrds from her P320 subcompact to diffuse an active shooter situation? Highly, highly unlikely. In that unlikely event, is throwing that 75yrd shot likely to diffuse the situation? No. Is it likely to worsen the situation for her and others? Yes. So is that shot worth it? Not a chance. In the circumstance she were pinned down on the floor in a movie theatre with the assailant between her and the door, then consider the simple process: “run” - she can’t, so next, “hide” a laying on the floor between the rows is hiding. If the attacker is standing at the front, simply hiding there might be enough for them to lose interest and leave without drawing attention to herself by attempting a low probability engagement. If the shooter advances, such hiding fails and her semi-secure spot may be revealed, THEN “fight.”
Pouring gasoline on an uncontrolled and unwanted fire is very seldom the right answer.
Run, hide, fight.