Leeches - Anki Manual (ankiweb.net)
I have 2,682 leeches, 15% of my deck.
They all became leeches due to interference, since every word is a synonym for some other word.
Since I have waited a couple years in some cases, I would imagine whatever interfered is now learned.
So, how can I automatically re-introduce these cards back into my studies?
Ideally, I would like to randomly pull from the leech pile, and when that happens up the leech threshold to 16, since 8 is already maxed out.
Are the leeches suspended (and likely very overdue)? Or are they active cards that just happen to be tagged as leech?
One approach is to unsuspend them, move all the leeches to its own deck, as a child of the deck you are actually studying, with a suitable review limit set on that deck to limit the number of cards. This may not be ideal if you are using decks to categorize things though.
You can also create a filtered deck with “tag:leech” with a set amount of cards each day. This requires manual rebuilding each day, but cards will return to its original deck once they are reviewed (they may not be automatically untagged though so it is not ideal).