They may have a rough plan, but also adjust as they discover issues with the ice. They may re route during the race too if a corner or area is a issue. The ruts can get deep enough to break through. Also they are plowing away the fluff during the race as needed.
I love when the ruts get deep enough, they upshift the bike in left handers. Made the mistake of doing that race on a lowered bike once, and figured out pretty quick that the extra suspension worked better for those conditions.
My niece and nephew sent me "The Story of Anvil" on DVD several Christmases ago. Arguably the first Metal band, fate was not kind to them. Their story plays out a lot like "This is Spinal Tap", except that they were real. Like Spinal Tap, they find redemption in Japan, and Lipps actually pays back to his sister the money she loaned him to record their latest album!
The millennial Wheelie https://www.facebook.com/crushed.mx/videos/vb.769004916539878/2246905358968035/?type=2&theater