If used regularly (at least once or twice/week) in "learning" mode, Flash! implements a detailed expanding-pattern-of-retreival mnemonic, of which research says:
"Wide potential application... evidence for the generality of this strategy."
Cull, William; Shaughnessy, John; Zechmeister, Eugene "Expanding understanding of the expanding-pattern-of-retrieval mnemonic: Toward confidence in applicability", in Journal of Experimental Psychology Applied, Dec 1996 Vol 2(4) PP 365-378.