Vocabulary Customization:  Learning the top 1000 words in your target language is a slam-dunk in terms of efficiency, but what about the next thousand words? And the thousand after that? When do frequency lists stop paying dividends? Generally, I’d suggest stopping somewhere between word #1000 and word #2000. At that point, you’ll get better gains by customizing. What do you want your language to do? If you want to order food at a restaurant, learn food vocabulary. If you plan to go to a foreign university, learn academic vocabulary