He's correct that repetition does drive things into our memory. This is the whole idea behind 'behavioral advertising' (google it for full explanation).

The theory: If a user has visited Amazon.com and browsed Digital Cameras lately, I'm going to drop a cookie and pass that to my ad server so that whenever he goes to Dictionary.com, I can show him an Amazon.com Digital Camera ad.

It's quite effective (has worked on me before).

I have metric anecdotes (that is, anecdotal remembered knowledge that, at some point in the past, I read about people who collected lots of data, analyzed it, and found a correlation.) I don't know whether that counts as an anecdote, as data, or somewhere in-between, though.