that and even if you roll a failure, its by degrees as well. there is a sharp difference in somethings, you make the car jump or you dont. but if you fail by one degree it may just be a broken axle and some impact damage compared to four degrees failure being a complete crushing of the drive cabin followed by an explosion when it all comes to a stop.<br/><br/>compared to say a navigation check, if you fail your only off by an hour or a few miles. if its larger, you might have gone in the absolute wrong direction.