There three main scenes, and one little scene. The little scene just jumps in on the mainscenes times, or something like that. Haven't really noticed it, since I'm only seeing two bands on it. But the main scenes have two scenes were bands play at the same time all the time, so you need to choose which one, but when the bands stop, there the third main scene which plays in the pauses of the two main scenes, so there's about an hour of nothing on two of the scenes, and the third scene has a band playing in that period of time, and when the bands on the twin scenes get on there's nothing on the third scene.
Like:
First scene: xxband 12.00 o'clock, stops at 13.00, starts again 14.00
Second scene: yyband 12.00 o'clock, stops at 13.00, starts again 14.00
third scene: zzband 13:05, stops at 13.55, starts again 15.05
That's pretty much the system of Wacken.
Do you at least know Morbid Tales and Into The Crypts of Rays? Those are essential! 
