I think a lot has been discussed here about what a leech is and what to do about them (Study more! No, that’s too much! Study less! Less, you fool!), but I wonder if anybody’s ever given much thought about what makes a leech a leech in the first place. What is it about that one item that causes it to not stick?
An item can be “hard,” or maybe easily confused with something else, but I feel these are not true leeches. For me, a real leech is an item that, when you see it, you know you’re going to get it wrong because you ALWAYS get it wrong. You first learned it a year ago, and since then it’s been bouncing back and forth between Guru and Apprentice, occasionally making it to Master if you’re lucky. When it pops up in your review, you have a Pavlovian reaction to it: Oh no, it’s this thing again.
You can use a self-study extension or an Anki deck or whatever your preferred SRS “cheat” is, but you know as soon as it’s been more than a few days it will just go away again. It’s not just that you can’t remember it, it’s more like there’s something specific about that one item that pushes a “forget” button in your brain, as if you had some deep, personal reason to keep it away. What is it about this one item? Is there really something about it your brain just hates on some level?