Alexander the Greedy

Some years after having bought it, I am reading Michael Wood's In the Footsteps of Alexander the Great. I saw at least one episode of the TV series during its original run in 1997, and remember enjoying it. The book seems to have been worked up from Wood's TV notes; as travelogue it's pretty thin, but it seems a good introduction to the story and I'm happily eating it up. I am curious as to how Alexander beat the Persians three times - at the battles of Granicus, Issus and Gaugamela - with what to my untrained eye appears to have been exactly the same strategy: attack the right flank at its weakest point and then veer left into the body of the Persian forces. You'd have thought they'd get wise to it.