Actually, the mods recommend that you do not do this, because it is NOT fair to read and vote on a story you know you aren't going to like. It's in the FAQs, and Poll Rules. We post warnings for that reason. How can that be impartial?
Each fic is averaged separately and added to the team total. Therefore it doesn't matter if one story only has 150 voters, and another has 300, they could each get 27/27. But it does matter when you vote low (overall) on an entry you are predetermined not to like.