Themes/trends do come and go (STEM, D&I, etc), but the core requirement is evidence of leadership and management. Whichever ‘flavour’ it takes is irrelevant. I would argue that the main PSB is somewhat of a lottery (try coming up with a number to two decimal places for a candidate again and again - I can explain further if you like), however if you get through pre-boarding (which is where the core L&M evidence needs to be obvious to the reader) you have a good shout due to the numbers game.
The 2RO should be gripped by a SNCO who knows what they are doing, if that is the case. It should be picked up in the debrief with the subject and stopped from getting off unit. I’ve seen this happen even once a report had been finalised.
My opinion on the current system is that the RAF is simply not prepared to invest the resource required to make a ‘perfect‘ system. You could have selection courses, tests, and a whole host of other ‘things’, however the current system in the main, does work. It’s the human element that causes problems.
I’ll finish by saying that if you are a SNCO, get yourself on a PSB. It’s bloody hard work, but you’ll learn a lot.