NASA did a study by riding jump seat and observing events on sixty flights, eight hundred ninety-nine deviations were observed (194 in checklist use, 391 in monitoring, and 314 in primary procedures). Included A320, 737, 757, 767, 777 and EMB 175/195.
Checklists and Monitoring in the Cockpit: Why Crucial Defenses Sometimes Fail
https://human-factors.arc.nasa.gov/p...010-216396.pdf