I suspect that much of that will depend upon the quality of instruction.
I think that I have twice ever had a conversation with Mr Davidson, and have never flown with him. However, a former student of mine did a course with him last year, was full of praise, and when I subsequently flew with my ex student this spring for other reasons, the learning seemed to have thoroughly stuck.
I have a lower opinion of some other instructors, who had delivered an intensive course - and a dangerously deficient pilot.
G