or is the knife attack scenario just far to unpredictable to successfully train for. has there been actual evidence/stories of people who have used such arts as kali, krav, systema

to successfully disarm a person? in a lot of the videos i see of these arts, the people are drilling endlessly, but there is little to no resistance at all. can the knife attack scenario be actually something we can train for? i mean there are soooooo many ways someone can attack you with the blade. its not like boxing where you have the jab, cross, hook, upper cut or muay thai with the elbows + knees, kicks. if someone really wanted to cut you up they can slash you from any angle and stab you from any angle with any sort of method. basically, if someone just bum rushes you with a machete or k-bar and you have no where to run, are you pretty much fucked?