You could try the Self-Study userscript, you can configure it to train leeches:
Other than that, no real advice, but I need to vent.
It can get so frustrating, I’m currently sitting on 206 leeches in Apprentice and 677 leeches in Guru stage, I keep reviewing the same items over and over again, to the point where I feel like my memory of these items gets worse and worse, and I feel like I can barely move forwards anymore.
Yestderday I did almost 500 reviews in a single day.