Out of interest, do you still do 'Ground Cats' in today's RAF?
They used to be annual for C Cats, 18 monthly for B Cats and 24 monthly for A Cats (or the 'Combat Ready' equivalents).
This periodic requirement to demonstrate adequate relevant knowledge was something of a pain (particularly for those of us who had to keep finding new questions to ask), but I'm sure were of more benefit than 14 exams sat once and promptly forgotten.
Apart from during Type Conversion, are civil airline pilots ever re-tested on theoretical knowledge? I know FIs have orals as part of their revalidation requirements, but does the average airliner driver have anything equivalent to satisfy?