This question also came up in the Google LARE group according to the answers there (which I agree with). In ‘real world’ practice the LA/designer would always do the punch list, however this puts liability on the LA – what if the LA missed something and signed off, then it could be the LA’s fault that it was not completed and be liable to pay fix/finish what ever was missed.
In theory, if the contractor does the punch list then the contractor is still liable should something be missed on the punch list. Both AIA and CLARB seem to be taking this tract. I am still not sure how exactly I would answer this on the test if it came up, it is basically a bad question.