I discovered Anki, probably the best flashcard maker, some months ago. I downloaded some Yiddish word files, and also created a library of the top 600 words used in the Yiddish Forverts. Plenty of vocabulary to learn. I got in the habit of testing myself everyday. I learned some more words, but I was put off by the number of words that I just could not memorize. The Anki sessions turned into a constant review of missed words, and no advancement to new words being introduced.. After about a month, I gave up on Anki and flashcards in general.
For me, the problem with flashcards is that they attempt to teach you vocabulary without any context. If you can't use the word in a sentence, then you are losing out on a learning opportunity. I have little problem picking up new vocab from Duolingo Yiddish, because the new words introduced are used in sentences which provide clues as to what the words mean.
Unless you are able to memorize large numbers of new words easily, I would not recommend using flashcards for language learning. You may learn new words, but you will be pressed to remember what the words mean after a few days.
Better to read yddish text with a dictionary, you're more or less guaranteed to retain the new vocabulary, as new words are not presented in a vacuum, as is the case with flashcards.
In the book Polyglot Notes. Practical Tips for Learning Foreign Language (available from Smashwords for $7.95 USD),
the author supports my personal findings about flashcards for language learning. The book is well worth reading to glean language learning tips and methods. (https://www.smashwords.com/books/view/1015030)
/ fluent 
/ getting better every day 
/ fan of 
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