I'm not qualified to truly understand this, but when Lex first interviewed Jim Keller, Jim basically said regarding processor design -- 'yeah, if you just guess the same result as last time, you get a 50% speed increase.'
The Weather Prediction Algorithm, weather will be the same as yesterday. Only wrong on transitions, very useful when you have runs of the same state. After that you implement a Markov Chain [1]
First Interview (where that poorly paraphrased quote resides): https://www.youtube.com/watch?v=Nb2tebYAaOA&t=13s
Second Interview: https://www.youtube.com/watch?v=G4hL5Om4IJ4