I think that's a good observation (your mileage may vary), but the time that flashcards are the must needful is when your first learning. Yet my first Chemistry university professors pointed out that, although most people imagined it was easiest to get started in a new field and harder to learn when you made it to me advanced classes, in fact, it's hardest to get started when the concepts are new and foreign and easier later when your just adding a deep understanding to what you have already fought to learn.