I’m no expert, but I can imagine most of that jump being sort of predetermined:
“If we’re going to do it, it needs to be *here*, and the landing needs to be *there*, and it needs to be a step-up because there’s no space for a big landing so we need people landing slow.
So the run in needs to go from there to there. We need x metres for a gap that’s worth all the bother and the loss of actual DH course, leaving y metres for flat bottom and run in.
Min. flat is z metres so the takeoff is going to have to be short and kicky or it means the gap’s going to be too small to make the all scaffolding worth the bother.”
And here we are.