Have you ever seen a YouTube video that was meant to teach you vocabulary in a foreign language? How did they go about helping you remember the words? There is a wide range of acceptable ways to teach vocabulary, but the following video is NOT one of them.
This video by Frenchpod 101 is my go-to example of a video that will NOT help you learn vocabulary. The reason it's so bad is because they simply recite a random word, repeat it one time, and then move on to the next word. They do this 2000 times without ever going back to review a single word in the list. So the video is a total waste of 4 hours.
We all know our brains require repetition in order to consistently store information, but not all repetition is made equal. Arguably the best kind of repetition we can get is spaced repetition. In spaced repetition programs, you will actually avoid reviewing a word until you are just about to forget it. This may sound counterintuitive, because it seems like you would want to review as many times as possible. However, it's actually not optimal to review a word while it is still fresh in your mind, because at that point you don't need to put in any work to recall it.The strongest memories are formed right when the word is on the verge of being forgotten when you're forced to really search through your brain to find that word. All the extra effort you put into remembering the word tells your brain that this is something you are going to have to remember for future use.
The other benefit of spaced repetition is time management. If you have 1000 flashcards, you don't have time to review each one every day (your time is better spent in comprehensible input or conversation practice). Forty to sixty cards per day is much more manageable, and spacing out your reviews allows you to divide your study time into much smaller chunks each day.
There are many digital Spaced Repetition Systems that you can use on your computer or mobile device to help you keep track of which words need to be reviewed and when. To see a list of them (and my opinions on each one) click here.