T-Rex: One day, Moriarty got the drop on Sherlock - let's say at the Reichenbach Falls - and he almost killed him!

T-Rex: And Sherlock's life flashed before his eyes!!

T-Rex: After Sherlock survived, of course, he deduced that SINCE his life flashed before his eyes, that therefore indicated that his mind not only stored a complete record of everything he'd ever seen, but that it was ALSO capable of retrieving and displaying it at insanely fast speeds. And this, he deduced, could be EXPLOITED.

T-Rex: He started flipping through books quickly, just glancing at each page!
Utahraptor: And then?

T-Rex: And THEN, whenever he needed access to that information, he'd just put himself in a dangerous position! During the "flash", he could study at his leisure, and deduce what he needed to know. Using this technique he'd instantly deduce how to survive an explosion DURING AN EXPLOSION!

T-Rex: Later on, criminals were like, man, maybe stealing a ruby and leaving an elaborate series of clues behind isn't actually worth it, and Sherlock would pop up and say "YOU WALKED PAST A CAFE I WAS AT FIVE YEARS AGO, JUST THOUGHT YOU SHOULD KNOW".
T-Rex: This is canon.