without referring to a printed checklist (this does have its place too).
In days of yore the student was required to learn the checks (Called Vital Actions Before take Off) by heart and the Before landing drills and others.
Checklists were for airline pilots.
Now we have airline cadets using airline type checklists for a Cessna 172 and without these checklists they are stuffed. Reading checklists that are usually lengthy and have superfluous content costs money and it all mounts up.