The original exam board for promotion in the technician rank was quite rigorous, consisting of a practical board covering all aspects of one's trade plus a multi-choice paper. Pass mark was 60%. One also had to pass an exam on a specialist subject, of one's choice, ie Canberra fuel system, hydraulics or electrical generating system. I think the pass mark was 80%
So a chief/tech would have three specialist subjects under his belt
It took two attempts for me to pass the cpl/tech exam and one attempt at senior tech although that rank became redundant in '64 and one wore sergeant's stripes.
Along with the rank re-structure of '64 came a complete, in my opinion, dumbing down of the examination standards. The practical boards were discontinued and all that was required was a pass mark on the multi-choice paper. By the early '70's the technical trades were awash with chief/techs and many, including myself were surplus to requirements, hence a generous redundancy package was accepted and I became a pensioner at 37!