All I can say is that slot designers know what they are doing. Creating the appearance of being close when you're really not close at all is one their greatest inventions.
I've heard that DOA1/2 uses actual reel striping. Not sure if that makes each individual spin in the bonus independent (i.e. reels could truly land anywhere) or if the final result is predetermined from the beginning based on theoretical probabilities. It might seem unlikely to get 4/5 wilds and keep missing the last one, but it's pretty easy if the frequent of a wild is only 1/10 or 1/15.