The SR-71 didn’t fly at Mach 5, it simply would have melted.
More to the point of what I’m saying is that a Cheeta doesn’t have a chance of catching you, if you are running across 100 yards of open ground (between buildings) that are 1000 yards from the Cheeta.
However, if the Cheeta has a way of predicting in advance when you’ll make your run, you’ll be dinner.
Maybe it didn’t fly at mach 5, but then it must not have done 3,500kts either. Just going by what others claimed it’s speed was.
Predictions are just that. Not a certainty. Maybe it will catch up at the right intersection, maybe not, Pilots have a funny way of being unpredictable in such a situation.