It is a total rackett.
If job seeking pilots have to get 4 of these a year just to keep 'current' then this is totally wrong.
CASA need to amend the CASR so that these things are only needed once a year.
If you refer to the CASR the obligation to test prospective 'sensitive' employees lies with the company that holds the AoC. They are only exempt if the person has had one in the last 90 days and it is negative.
So another example of 'pay to fly' by the charter companies.
Biggles