It's not that hard to get it right!
Provided you have the right people, with the right training and experience doing the job, and those people aren't burdened by the collective stresses of fatigue, modern rostering preactices, pay not comensurate with responsibility, degraded ATC services and engineering support, reduced autonomous authority, overloaded/overworked ground support personel, and ever increasingly complicated SOPs and legislation.
Even with all of those things most of us can cope well, but every pilot group has a few stars, a large proportion of competent pilots, and a few who drag their heels. If you end up with two crew together who are from the last group.....it's too much for them and the results will are starting to show themselves.