I think you guys are misunderstanding what I meant by "gut reaction".  I didn't mean your INITIAL reaction ... I mean it's how you feel about something on a level that you might not even be able to quantify.  Sometimes, it's when someone asks you why you like something, and your only response is "I don't know.  I just DO."  That sort of thing.  It's a visceral response, as opposed to anything quantifiable ... which is what I meant when I said that they are exercises in justifying that reaction.  People just don't think in terms of scores, they just like something, don't like it, or don't really care.
Yes, I frequently know what direction I'm going to lean in regarding a game in about half an hour to an hour.  But that's only in terms of positive or negative ... the SCORING itself is a much longer process for me.  Mainly because I have my own criteria that I've exstablished to keep my reviews as consistent as possible.  Sometimes, I'm surprised at the score I end up at, because my initial "guess" ends up being so different.