I advocate the refresher courses although every 3 years seems a little excessive and ineviatebly will be very expensive for the airports.
It had been mooted that the Colleges could send instructors to the airports, but, for a change, I concur with His Gonzoness, a lot can be gained from refresher courses.
The college environment is a the appropriate place for such courses, not only can one pass on ones infinent wisdom to others but it allows an open discussion of ideas (and a few days on the bevvy at someone elses expense
).