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).