They train for it. When people who have ejected talk about it they basically say it's automatic. Things go south they pull the handle on instinct.

One has to be trained to do it, the untrained tendency is to wait too long. There's a USAF film on Youtube titled "Ejection Decision" that discusses this and shows how little time there is to make that choice.

So fast they shit their pants as the chutes were deployed.

https://en.wikipedia.org/wiki/OODA_loop

At this point you barely "make the decision". They train and train and train to the point where it's automatic as soon as they know there's no way to avoid the crash.

    if(oh shit) { pull(); }

[dead]