I am interesting knowing people's strategy here about the last questions on the GMAT
In my mind, questions 27-37 are much more important than 17-27.
for the reason that they are not going to put experimental questions at the end of the test, they want everybody to have at least some time to really try to answer the question, this is the only way to have a fair opinion about the difficulty of the question.
Moreover, you should consider that few people won't even finish the GMAT so they won't even answer those question.
So the consequence is that from question 27 to question 37, a maximum of questions should be real...so it's worth taking time to answer it
However, it would very strange that those questions would be 1-5, we can suppose to meet some at 5-15...however, it doesn't change the result : don't rush for the last questions !
Other ideas and opinions are welcome about this subject.