> I'm not sure if vocabulary size matters once you reach around 25,000 words.

This is what I was thinking. I scored 34K, and rarely encounter a word that I don't understand in regular speech or reading. I also know several thousand jargon words, none of which were on that test. I know what I need to know. Memorizing another 16K words to reach Shakespeare's magical 50K (and feel good about myself) would be a waste of precious mental resources.