Ever since I was a student, it's been drilled in me to use a checklist. But recently I was flying with a more experienced test pilot, and he tells me that paper checklist can do more harm than good because you're not thinking when you're using it. You simply become a robot and just go through a list without questioning why? He thinks it's better for you as the PIC to have and practice your own cockpit flow in every phase of flight. Is he right? what's been your experience?