That's a good approach. I suspect, for others (and in my experience) when one consistently comes to The Difficult Card, they might have spent more time remembering that it was hard to remember than remembering the answer.

Or, they agonize over the answer for too long, then when they flip it over, they think "Of course!" but move along almost immediately.

And I think you're right also; when you finally get it, it's hard to forget.