This is an aggregate, but seriously, game reviewers almost NEVER complete the games they're paid to review anymore. These people are literally the most casual people who work in the industry. I think Age of Conan reviewers played an average of two hours before passing judgement, one gave Darkfall Online a 2/10 after playing for 5 minutes and getting PK'd.
One of the X/Y reviewers even complained that ITS TOO HARD TO REMEMBER WHAT TYPE ALL OF THE POKEMON ARE GAMEFREAK ACTUALLY EXPECTS US TO DO THAT? As if he wants the ability which will hit enemies for SE damage to be highlighted in green and the NFE ones to be highlighted in red.
Nowadays reviewers just go on reddit, find out the popular opinion, then regurgitate whatever will make fans happy, then give it a 8-9/10. And if it's a Japanese game they'll throw in a snide comment about those dirty nips living in the past.