How valuable are Flash Cards??

Its getting to crunch time and I have not finished my first review of the material, (still have half of Fixed Income, Ethics, Derivatives, Alt and PM to go), I have tried to draw up flash cards as I go along on the study routine but they seem to be time consuming to make!

Just wanted to know if everyone finds them invaluable or a must-have for memorizing? Bearing in mind that CFA Level 2 has way more to memorize than Level 1 did!

The value in flashcards is in the writing, not in the reviewing.

They can be quite valuable.