When I was forcibly 'retired' from the CAR 217 airline system I did a single-pilot IR renewal on a light twin. The ATO was very experienced in that field and I am sure could have used the time to bring me up to speed on the shortcomings of that category of aeroplane. Some performance questions would have been in order, even though they are not part of the CASA form. Instead, I got a grilling on all sorts of obscure regulations.
Having proved that I only knew about 50% (at best) of these regulations, presumably the 50% that I did know was the necessary stuff, because we then proceeded to flight test. So I dunno what the point of the obscure questions was, because I promptly forgot all of it anyway.
The flight test took 45 minutes and was a total walk in the park, even though I only had 2 hours on that aircraft type. The probable reason for the 45 minutes was that the operator was paying, not because I was acing the test.
IMHO the CASA approach to the Instrument Rating has far too much emphasis on the regulations and not enough on raw flying skills. Also the test seems to require no understanding of performance, the assumprtion being that you retain this stuff from your initial studies.