As a flight instructor, what did I learn giving pilots their Biennial Flight Reviews (BFR)? That there are a lot of private pilots out there who could use some extra training even after they get their private pilot’s license.
By the way, “biennial” meant every two years. I think the FAA thought that pilots suddenly became so stupid it had to simply rename it a “Flight Review.” Then tack on “every two years” after that, so pilots could tie both shoe laces.
Seriously, who comes up with this stuff? For years, a BFR was known to all pilots as a Biennial Flight ...