Picking up on your own errors takes vigilance and a finely tuned suspicion of that feeling that something is not quite right. Assume nothing, check everything and then check again.
Absolutely, who could argue with that? But is it possible to maintain such high standards of vigilance 4 sectors/day 5 days/week?
I suspect that not only is it not possible, but also with such concentrated schedules one even risks loosing control of when to apply said vigilance, especially when one conscientiously attempts to be perfect and make no mistakes. I have sometimes wondered the safest pilots allow themselves to reduce their concentration and accept small errors during relatively benign phases of flight to help ensure a sharp mind when it matters most. Would a training department find that acceptable though?