I have definitely wasted lots of time creating and reviewing cards for words that I never see again (the long tail) or don't strictly need to know. But the feel

I have definitely wasted lots of time creating and reviewing cards for words that I never see again (the long tail) or don't strictly need to know. But the feeling of coming across a word that you learned and -knowing- it is amazing. It also helps if you enjoy the process of creating and reviewing cards - tending to your knowledge garden, so to speak.