I've been experimenting with Anki recently. I loaded up a deck of popular fonts, with the goal being to memorize them to the point where I could recognize them in the real world. Each card contains the sentence, "The quick brown fox jumped over the lazy dog," and you have to identify what font it's written in.
The first day was really tough; I missed cards over and over again. 20 new cards (the default) is probably too many for this type of study. But I kept at it, once per day, and today (a week later) I can recognize nearly every font in the deck, and the ones that I have trouble with are very similar to other fonts (which is a useful thing to know in its own right; you can start to group fonts into "families" with a common ancestor). Pretty cool!
There's just one problem: so far, this hasn't translated into any ability to recognize fonts in the real world. I can think of a few reasons why. First, there are a LOT of fonts out there; even the "most popular" ones don't show up all that frequently. This is especially true for business logos, which like to use unusual fonts to make themselves stand out. Secondly, I think studying by memorizing a single sentence has caused me to "overfit!"
For example, there's a font that I can instantly recognize (Minion Pro) by how the 'T' and 'h' look together at the start of the sentence. I don't pay attention to anything else about the font, because that single feature is enough to distinguish it from the rest of the deck. And this turns out to be true for most fonts: Today Sans has a funny-looking 'w', Syntax has a funny-looking 'x', etc. So if I see a logo written in Today Sans, but it doesn't contain a 'w', I can't recognize it! Similarly, because the cards only contain the one sentence, which is entirely lowercase except for the 'T', I can't identify any fonts from an uppercase writing sample. What I can do is say, "Hmm, I don't know what that font is, but it definitely has a lot in common with Myriad..." and then I look it up and find out that the actual font is Warnock, which was designed by the same guy (Robert Slimbach) who designed Myriad.
So yeah, Anki is pretty cool, but an unintended side effect is that it can give you a striking sense of how a classification algorithm "feels" from the inside. :)