A good keen F/O with a professional attitude will have been practicing being a Captain from the RHS for a very long time before his upgrade. He should have been trying to think like a skipper and come up with his own solutions to problems. If something arises he should assess it as if he was in the LHS, come up with an answer in his own mind, see what the capt did and look at the out come. He should be asking as many questions as possible coming up to his upgrade, he should be asking the line guys how to do the tech log, how to apply the MEL and continually ask himself 'what would I do now if x happened'. This is the attitude that will sail you briskly through your upgrade interview AND course with minimal fuss. On the other hand, I fly with some who I can spot a mile off will fail. They are the ones who, with just a couple of months to upgrade are happy to sit there reading the Gulf News, chatting up the crew and generally have 'sloping shoulders' not giving a sh1t.
Spot on!
It's very little about flying, and a whole lot about managing.