What makes a vocabulary review queue feel manageable?

I built Recordar Palabras after noticing that saving every unfamiliar word made review less useful, not more.

The rule that has worked best for me is to keep the queue small enough to finish: save words that matter in context, write or generate a concise definition, and stop adding new ones when reviews start piling up.

How do you decide which words are worth keeping—and when a vocabulary list has become too large?

Disclosure: I’m the maker of Recordar Palabras, which launches here on August 11.