[Wicher]

Well, I can tell you, if you win a race because it is only when you're in your "extra time" that the wind finally picks up, it doesn't really feel like winning. Happened to me in a course race.

The weather during the different time frames may vary wildly. It may work to your advantage, or to your disadvantage — on average, it will be canceled out. But rating/handicap systems sure make that there's more luck involved than in one-class races. Not that that's a bad thing.