Some have 2-, 3-, 4000, sometimes 5000 hours and lacks basic knowledge in aviation.
I would suggest that rather than not knowing it they have simply forgotten it over the last 10 or so years since they did their last CPL/ ATPL exams. Where as a cadet is straight out of flying school with all that info still fresh in their heads. You would probably also find that a 5000hr regional or GA pilot hasn't had to sit down and do any serious study for several years and so they take a bit longer to get into study mode than say a Cadet who has just done 18months or so of intense study and training.