No, because during training runs nobody in their right mind goes so fast with such crappy form that they need to stop abruptly at an obstacle. They slow down as they approach it and then go over/around it at a reasonable speed. Besides, on any given day there are hundreds of such "obstacles" on the trail ant seemingly random locations; they are called other users of the trail. Remember, with the exception of the BTMR and PPM, downhill users need to yield to uphill users.
During race day, only a handful of folks can actually go very fast on the downhill. You can see them at the awards ceremony. The rest of us are just doing our best to keep the rubber side down.