I am a GMAT trainer from Calcutta, INDIA. In my experience the Official Guides are only indicative of the nature of the questions and the relative weights of question sub types. For example, if we look at "evaluate the argument" type of questions in CR, we find that while OG 11
had only 2 questions of this type, OG 12
and OG 13
have 13 and 21 questions respectively. Thus we can conclude that, now, questions of this type are tested more frequently.
However, since the OGs contain questions that span the the entire score range, only a few OG questions are of the 700+ standard. Moreover, all these are retired questions, and are somewhat different from the actual questions that are being written now. To do well on the GMAT, on must solve questions that are similar to the ones that have recently been tested on the GMAT.
Hence, my advice to you is that you do not limit yourself to just the OG, but, rather, look at other sources of questions.