In my varied career I have met many an electrician who has worked in a small section of his trade for many years and was frankly rather lacking in other areas. However they did their job well.
The problem is when they move areas of the trade and suddenly are confronted with something they have never seen before.
The correct answer is of course ask. When the problem arises is where they are too proud to ask so make avoidable mistakes.
While working on the Building of Sizewell Power Station I was rather dismayed to see apprentices who had spent the best part of their time fitting cable tray. They only had what they learnt in college to give them any insight as to what other electricians did.
I myself many years ago went back to college to do my C&G2391 when I realised I was measuring earth loop impedance and writing down the readings without knowing if these readings would be considered as a pass or a fail.
So I can understand why some one would be worried when taking a sidewards move into new aspects of being an electrician.
I found
this link interesting and it does roughly say what is expected.
The main problem to most is we are tested on what we should do rather than what we really do. In all my time only when working for a petrol chemical plant in rock savage were the rules on safe isolation and proving dead strictly followed. Not having a proving unit to hand was instant withdrawal of site pass.
So there is only one route to pass these tests and that's through a training establishment. They have been designed as part of a training system and to try to pass these tests without formal training is likely to be a failure.
I remember being given a board to test. I failed the sockets as the impedance was too high. I was told this was an error as it was within the regulation requirements to which I answered yes but this socket is only 1 foot from the consumer unit there is clearly a fault when the impedance is so different. It seemed the board had resistors to emulate a normal house. I pointed out if the sockets had been used it would likely have resulted in a fire so I was right to fail them. Reluctantly the tester agreed but this does show how the real world is different from the college world and really one should take these tests as designed as part of a college course.