The only place i can see where top four MIGHT be a good idea is 3rd grade, where the divisions are essentially a hat pick and you have no idea who the best teams are going to be (like two years ago, when the top two teams in the league were in the same division, TYAA Red and Jenks Silver).  But after that, when divisions are "evenly" distributed based on how you finished the previous year, then i think top 3 is plenty.