Tourney Conditions?

[Harpo]

While playing The Judge tourney this week I noticed something that I don't know if this was true every week. The Pro rounds consisted of 3 NW rounds and then a Gusty round. I happen to click on a wrong event to see what the last round was before I played (the 4th). It happens to turn out that all the Chal. events in all levels had 4 NW rounds. Any idea why? Not complaining but just seemed odd.